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Mr. G. Netaji: VR23 C LAB SOLUTIONS

R23 C LAB SOLUTIONS

COMPUTER PROGRAMMING LAB

Exercise 2: Converting algorithms/flowcharts into C Source code
  1. Sum and average of 3numbers.
    2. #include<stdio.h>
#include<conio.h>
int main()
{
    int a, b, c, sum;
    float avg;
    clrscr();
    printf("Enter values of a,b, and c: \n");
    scanf("%d %d %d", &a, &b, &c);
    
    sum = a + b + c;
    
    avg = sum / 3;
   
    printf("Sum = %d \n", sum);
    printf("Average = %.2f", avg);
    return 0;
}
  2. Conversion of Fahrenheit to Celsius and vice versa.
    3. //Conversion of Fahrenheit to Celsius
#include<stdio.h>
#include<conio.h>
void main()
{
 float celsius, fahrenheit;
 clrscr();

 printf("\n Enter Temp in Fahrenheit : ");
 scanf("%f", &fahrenheit);

 celsius = (fahrenheit-32) / 1.8;
 printf("\n Temperature in Celsius : %.2f ", celsius);

 getch();
}
    //Conversion of Celsius to Fahrenheit
#include<stdio.h>
#include<conio.h>
void main()
{
 float celsius, fahrenheit;
 clrscr();

 printf("\n Enter Temp in Celsius : ");
 scanf("%f", &celsius);

 fahrenheit = (1.8 * celsius) + 32;
 printf("\n Temperature in Fahrenheit : %.2f ", fahrenheit);

 getch();
}
  3. Simple interest calculation.
    4. #include<stdio.h>
#include<conio.h>
int main()
{
int p,r,t,int_amt;
clrscr();
printf("Input principle p, Rate of interest r & time in years t to find simple interest: \n");
scanf("%d%d%d",&p,&r,&t);
int_amt=(p*r*t)/100;
printf("Simple interest = %d",int_amt);
return 0;
}
Exercise 3: Simple computational problems using arithmetic expressions.
  1. Finding the square root of a given number.
    2. #include<stdio.h>
#include<conio.h>
#include<math.h>
int main() {
   double number, squareRoot;
   clrscr();
   printf("Enter a number: ");
   scanf("%lf", &number);
   squareRoot = sqrt(number);
   printf("Square root of %.2lf =  %.2lf", number, squareRoot);
   return 0;
}
  2. Finding compound interest.
    3. #include<stdio.h>
#include<conio.h>
#include<math.h>
int main()
{
    double principle, rate, time, CI, n;
    clrscr();
    printf("Enter principle (amount): ");
    scanf("%lf", &principle);

    printf("Enter time in years: ");
    scanf("%lf", &time);

    printf("Enter annual rate of interest: ");
    scanf("%lf", &rate);
    
    printf("Enter the number of times that interest is compounded annually: ");
    scanf("%lf", &n);

	A = principle * pow((1 + rate /(100*n)), n * time);
    printf("final amount with compound interest %lf", A);
    
    /* Calculate compound interest */
    CI = A - principle;

    /* Print the resultant CI */
    printf("Compound Interest = %.2lf", CI);

    return 0;
}
  3. Area of a triangle using heron’s formulae.
    4. Steps to find the area of a triangle using Heron's formula
Let A, B and C be the length of three sides of a triangle.

Calculate the semi perimeter of the triangle.
Semi-Perimeter of triangle(S) = (A + B + C)/2
    
Now, we can calculate the area of triangle using below mentioned formula.
Area of Triangle = √ S(S-A)(S-B)(S-C)) 
Where, S is the semi-perimeter that we calculated in first step.

#include<stdio.h>
#include<conio.h>
#include<math.h>
int main()
{
    float side1, side2, side3, s, area;
    clrscr();
    printf("Enter the length of three sides of triangle\n");
    scanf("%f %f %f", &side1,&side2,&side3);
    s = (side1 + side2 + side3)/2;
    area = sqrt(s*(s-side1)*(s-side2)*(s-side3));
    printf("Area of triangle : %0.4f\n", area);
    return 0;
}
  4. Distance travelled by an object.
    5. #include<stdio.h>
#include<conio.h>
void main()
  	{
     float u,a,t,v,s;
     clrscr();
     printf("\n Enter initial velocity u: ");
     scanf("%f",&u);
     printf("\n Enter acceleration a: ");
     scanf("%f",&a);
     printf("\n Enter time required t: "); 
     scanf("%f",&t); 
     s=u*t+(1/2)*a*t*t;
     printf("\n The distance traveled is : %f ",s);
     getch();
    }
Exercise 4: Simple computational problems using the operator’ precedence and associativity
  1. Evaluate the following expressions.
    2. 1)	Evaluate the following expressions.
    
	a.	A+B*C+(D*E)+F*G
    
	b.	A/B*C-B+A*D/3
    
	c. A+++B---A
    
	d. J= (i++) +(++i)
    

#include<stdio.h>
#include<conio.h>
int main() {
    
    int A=1,B=2,C=3,D=4,E=5,F=6,G=7,a,b,c,J,i=1;
    
    a=	A+B*C+(D*E)+F*G;
    printf("a= %d",a);
    
    //if u take float, u will get exact output
    b=A/B*C-B+A*D/3;
    printf("\n b= %d",b);
    
    c=A+++B---A;
    printf("\n c= %d",c);
    
    J= (i++) +(++i);
    printf("\n J= %d",J);
    
    return 0;
}
  2. Find the maximum of three numbers using conditional operator.
    3. #include<stdio.h>
#include<conio.h>
    void main()
    {
        int a, b, c, big ;
     	clrscr();
        printf("Enter three numbers : ") ;
     
        scanf("%d %d %d", &a, &b, &c) ;
     
        big = a > b ? (a > c ? a : c) : (b > c ? b : c) ;
     
        printf("\nThe biggest number is : %d", big) ;
        getch();
    }
  3. Take marks of 5 subjects in integers, and find the total, average in float
    4. #include<stdio.h>
#include<conio.h>
int main()
{
    int eng, phy, chem, math, comp; 
    float total, average, percentage;

    /* Input marks of all five subjects */
    printf("Enter marks of five subjects: \n");
    scanf("%d %d %d %d %d", &eng, &phy, &chem, &math, &comp);

    /* Calculate total, average and percentage */
    total = eng + phy + chem + math + comp;
    average = total / 5.0;
    percentage = (total / 500.0) * 100;

    /* Print all results */
    printf("Total marks = %.2f\n", total);
    printf("Average marks = %.2f\n", average);
    printf("Percentage = %.2f", percentage);

    return 0;
}
Exercise 5: Problems using conditional statements.
  1. Write a C program to find the max and min of four numbers using if-else.
    2. #include<stdio.h>
#include<conio.h>
int main() {
    int a,b,c,d; 
    printf("Enter the Four Numbers :"); 
    scanf("%d %d %d %d",&a,&b,&c,&d); 
    if(a>b && a>c && a>d) 
    { 
        printf("%d is max \n",a); 
    } 
    else if(b>c && b>d)
    { 
        printf("%d is max \n",b); 
    } 
    else if(c>d)
    { 
        printf("%d is max \n",c); 
    }         
    else
    {
        printf("%d is big \n",d);
    }
    
    if(a<b && a<c && a<d) 
    { 
        printf("%d is min",a); 
    } 
    else if(b<c && b<d)
    { 
        printf("%d is min",b); 
    } 
    else if(c<d)
    { 
        printf("%d is min",c); 
    }         
    else
    {
        printf("%d is min",d);
    }
    return 0;
}
  2. Write a C program to generate electricity bill.
    3.   
Conditions:

    For first 50 units – Rs. 3.50/unit
    For 51 - 150 units – Rs. 4.00/unit
    For 151 -250 units – Rs. 5.20/unit
    For units above 250 – Rs. 6.50/unit
    
#include<stdio.h>
int main()
{
	float bill, units;

	printf("Enter the units consumed=");
	scanf("%f",&units);

	if(units<=50 && units>=0)
	{
		bill=units*3.50;
		printf("Electricity Bill=%0.2f Rupees",bill);
	}
	else if(units<=150 && units>50)
	{
		bill=50*3.50+(units-50)*4;
		printf("Electricity Bill=%0.2f Rupees",bill);

	}
	else if(units<=250 && units>150)
	{
		bill=50*3.50+100*4+(units-150)*5.20;
		printf("Electricity Bill=%0.2f Rupees",bill);

	}

	else if(units>250)
	{
		bill=50*3.50+100*4+100*5.20+(units-250)*6.50;
		printf("Electricity Bill=%0.2f Rupees",bill);

	}
	else
	{
	printf("Please enter valid consumed units...");
	}
	return 0;
}
  3. Find the roots of the quadratic equation.
    4.  
# include<stdio.h>
# include<math.h>
#include<conio.h>
int main () {
    float a,b,c,r1,r2,d;
    clrscr();
    printf ("Enter the values of a b c: ");
    scanf (" %f %f %f", &a, &b, &c);
    
    d= b*b - 4*a*c;
    
    if (d>0) {
        r1 = -b+sqrt (d) / (2*a);
        r2 = -b-sqrt (d) / (2*a);
        printf ("The real roots = %f %f", r1, r2);
    }
    else if (d==0) {
        r1 = -b/(2*a);
        r2 = -b/(2*a);
        printf ("Roots are equal =%f %f", r1, r2);
    }
    else
        printf("Roots are imaginary");
    
    return 0;
}
  4. Write a C program to simulate a calculator using switch case.
    5.  
#include <stdio.h>
#include<conio.h>
int main(){
    char ch;
    int a, b, result;
    clrscr();
    printf("Enter an Operator (+, -, *, /, %): ");
    scanf("%c", &ch);
    printf("Enter two operands: \n");
    scanf("%d %d", &a, &b);
    
    switch(ch){
        case '+':
            result = a + b;
            printf("%d + %d = %d", a, b, result);
            break;
        case '-':
            result = a - b;
            printf("%d - %d = %d", a, b, result);
            break;
        case '*':
            result = a * b;
            printf("%d * %d = %d", a, b, result);
            break;
        case '/':
            result = a / b;
            printf("%d / %d = %d", a, b, result);
            break;
        case '%':
            result = a % b;
            printf("%d mod %d = %d", a, b, result);
            break;
        default:
       		printf("choose proper menu");
            break;
    }
    return 0;
}
  5. Write a C program to find the given year is a leap year or not.
    6.  
#include <stdio.h>
#include<conio.h>
    void main() {  
        int year;  
        clrscr();
        printf("Enter a year: ");  
        scanf("%d", &year);  
        if((year%4==0) && ((year%400==0) || (year%100!=0)))  
        {  
            printf("%d is a leap year", year);  
        } else {  
            printf("%d is not a leap year", year);  
        }  
       
    }  

or

#include <stdio.h>
int main() {
   int year;
   printf("Enter a year: ");
   scanf("%d", &year);
   if (year % 400 == 0) {
      printf("%d is a leap year.", year);
   }
   // not a leap year if divisible by 100
   else if (year % 100 == 0) {
      printf("%d is not a leap year.", year);
   }
   else if (year % 4 == 0) {
      printf("%d is a leap year.", year);
   }
   else {
      printf("%d is not a leap year.", year);
   }

   return 0;
}
Exercise 6: Problems using control statements.
  1. Find the factorial of given number using any loop
    2. //using while loop
#include<stdio.h>
#include<conio.h>
int main(){
  int f=1,num;

  printf("Enter the number : ");
  scanf("%d",&num);

  while(num>0)
  {
      f=f*num;
      num--;
  }
  printf("The Factorial is: %d\n",f);
return 0;
}

//using for loop
#include<stdio.h>
#include<conio.h>
void main(){
  int i,f=1,num;

  printf("Enter the number : ");
  scanf("%d",&num);

  for(i=1;i<=num;i++)
  {
      f=f*i;
  }
  printf("The Factorial of %d is: %d\n",num,f);
}
  2. Find the given number is a prime or not.
    3. #include<stdio.h>
int main() 
{
  int n, i, flag = 0;
  printf("Enter a positive integer: ");
  scanf("%d", &n);
  if (n == 0 || n == 1)
    flag = 1;

  for (i = 2; i <= n / 2; ++i) 
  {
    if (n % i == 0) {
      flag = 1;
      break;
    }
  }

  if (flag == 0)
    printf("%d is a prime number.", n);
  else
    printf("%d is not a prime number.", n);

  return 0;
}
  3. Compute sine and cos series.
    4.  
The formula of Sine Series is 
sin(x) = x - (x*x*x)/3! + (x*x*x*x*x)/5! - (x*x*x*x*x*x*x)/7!
for Example,
Let the value of x be 50.

x= 50 * pi/180 = 50 * (3.14/180) = 0.8722

So, Radian value for 50 degree is 0.8722.
sin(0.8722) = 0.8722 - (0.8722*0.8722*0.8722)/3! + (0.8722*0.8722*0.8722*0.8722*0.8722)/5!...


//Compute Sine Series 
#include<stdio.h>
int main()
{
    int i, n;
    float x, sum, t;
    printf(" Enter the value for x : ");
    scanf("%f",&x);
    printf(" \n Enter the value for n : ");
    scanf("%d",&n);
     
    x=x*3.14159/180;
    t=x;
    sum=x;

    for(i=1;i<=n;i++)
    {
        t=(t*(-1)*x*x)/(2*i*(2*i+1));
        sum=sum+t;
    }
     
    printf(" The value of Sin(%f) = %.4f",x,sum);
    return 0;
}


The formula of Cosine Series is 
cos(x) = 1 - (x*x)/2! + (x*x*x*x)/4! - (x*x*x*x*x*x)/6!
for Example,
Let the value of x be 50.

x= 50 * pi/180 = 50 * (3.14/180) = 0.8722

So, Radian value for 50 degree is 0.8722.
cos(0.8722) = 1 - (0.8722*0.8722)/2! + (0.8722*0.8722*0.8722*0.8722)/4!...


//Compute Cosine Series 
#include<stdio.h>
int main()
{
    int i, n;
    float x, sum=1, t=1;
    clrscr();
     
    printf(" Enter the value for x : ");
    scanf("%f",&x);
     
    printf(" Enter the value for n : ");
    scanf("%d",&n);
     
    x=x*3.14159/180;
     
    /* Loop to calculate the value of Cosine */
    for(i=1;i<=n;i++)
    {
        t=t*(-1)*x*x/(2*i*(2*i-1));
        sum=sum+t;
    }
     
    printf(" The value of Cos(%f) is : %.4f", x, sum);
    return 0;
}
  4. Checking a number palindrome.
    5. #include<stdio.h>
int main() {
  int n, rev = 0, rem, org;
    printf("Enter an integer: ");
    scanf("%d", &n);
    org = n;

    while (n != 0) {
        rem = n % 10;
        rev = rev * 10 + rem;
        n /= 10;
    }

    if (org == rev)
        printf("%d is a palindrome.", org);
    else
        printf("%d is not a palindrome.", org);

    return 0;
}
  5. Construct a pyramid of numbers.
    6. // Half Pyramid
#include<stdio.h>>
int main() {
   int i, j, rows;
   printf("Enter the number of rows: ");
   scanf("%d", &rows);
   for (i = 1; i <= rows; ++i) {
      for (j = 1; j <= i; ++j) {
         printf("%d ", j);
      }
      printf("\n");
   }
   return 0;
}


// Full Pyramid
#include<stdio.h>>

int main() {
    // Write C code here
    int i,j,k,l;
    for(i=1;i<=5;i++)
    {
        for(k=5;k>=i;k--)
        printf(" ");
        for(j=1;j<=i;j++)
        printf("%d",j);
        for(l=j-2;l>0;l--)
        printf("%d", l);
        printf("\n");
    }
    

    return 0;
}
Exercise 7: Using arrays.
  1. Find the min and max ofa1-D integer array.
    2. #include<stdio.h>>
int main()
{
    int A[10], i, max, min, n;
    printf("\n\nFind maximum and minimum element in an array :\n");
    printf("Input the number of elements to be stored in the array :");
    scanf("%d",&n);
   
    printf("Input %d elements in the array :\n",n);
    for(i=0;i<n;i++)
    {
	  printf("element - %d : ",i);
	  scanf("%d",&A[i]);
	}
    max = A[0];
    min = A[0];

    for(i=1; i<n; i++)
    {
        if(A[i]>max)
        {
            max = A[i];
        }


        if(A[i]<min)
        {
            min = A[i];
        }
    }
    printf("Maximum element is : %d\n", max);
    printf("Minimum element is : %d\n\n", min);
}
  2. Perform linear search on 1D array.
    3. #include<stdio.h>>
int main()
{
    int A[100], search, i, number;
    printf("Enter the number of elements in array\n");
    scanf("%d",&number);
    printf("Enter %d numbers\n", number);
    for ( i = 0 ; i < number ; i++ )
        scanf("%d",&A[i]);
    printf("Enter the number to search\n");
    scanf("%d",&search);
    for ( i = 0 ; i < number ; i++ )
    {
        if ( A[i] == search )  
        {
            printf("%d is present at location %d.\n", search, i+1);
            break;
        }
    }
    return 0;
}
  3. The reverse of a1D integer array.
    4. #include<stdio.h>>
int main()
{
    int n, i,j, A[100];
    
    printf("Enter the number of elements in array\n");
    scanf("%d", &n);
    
    printf("Enter the array elements\n");
    for (i = 0; i < n ; i++)
        scanf("%d", &A[i]);
    printf("reverse elements in array\n");
    for (j = n - 1; j >= 0; j--)
        printf("%d \n",A[j]);
  4. Eliminate duplicate elements in an array.
    5. #include<stdio.h>
int main(){
    int a[10],i,j,k,n;
    printf("Enter size of the array\n");
    scanf("%d",&n);
    printf("Enter Elements of the array:\n");
    for(i=0;i<n;i++){
        scanf("%d",&a[i]);
    }
    printf("Entered element are: \n");
    for(i=0;i<n;i++){
        printf("%d ",a[i]);
    }
    for(i=0;i<n;i++){
        for(j = i+1; j<n; j++){
            if(a[i] == a[j]){
                for(k = j; k<n; k++){
                    a[k] = a[k+1];
                }
                j--;
                n--;
            }
        }
    }
printf("\nAfter deleting the duplicate element the Array is:\n");
    for(i=0;i<n;i++){
        printf("%d ",a[i]);
    }
return 0;
}
  5. Find 2’s complement of the given binary number.
    6. #include<stdio.h>
int main(){
   char num[10], A[10], B[10],C[10];
   int i,j,k, carry = 1;
   printf("Enter the binary number");
   gets(num);
   for(i = 0; num[i]!= '\0'; i++){
      if(num[i] == '0'){
         A[i] = '1';
      }
      else if(num[i] == '1'){
         A[i] = '0';
      }
   }
   A[i] = '\0';
   printf("1's complement of binary number is %s", A);
   for(j =i - 1; j >= 0; j--){
      if(A[j] == '1' && carry == 1){
         B[j] = '0';
      }
      else if(A[j] == '0' && carry == 1){
         B[j] = '1';
         carry = 0;
      }
      else{
         B[j] = A[j];
      }
   }
   B[i] = '\0';
  // Below code only works if u take all zeros as input 0000
   if(B[0]=='0'&& carry == 1)
      {
      	for(k =0; k<i; k++)
      	{
      		C[k+1]=B[k];
       }
        C[0] = '1';
        C[i+1]='\0';
      printf("\n 2's complement of binary number is %s",C);	 
      }
   else
   {
   printf("\n 2's complement of binary number is %s",B);
   } 
   return 0;
}
Exercise 8: arrays and strings.
  1. Addition of two matrices.
    2. #include<stdio.h>
int main() {
  int r, c, A[10][10], B[10][10], sum[10][10], i, j;
  printf("Enter the number of rows: ");
  scanf("%d", &r);
  printf("Enter the number of columns: ");
  scanf("%d", &c);

  printf("\nEnter elements of A matrix:\n");
  for (i = 0; i < r; ++i)
    for (j = 0; j < c; ++j) {
      printf("Enter element a%d%d: ", i + 1, j + 1);
      scanf("%d", &A[i][j]);
    }

  printf("Enter elements of 2nd matrix:\n");
  for (i = 0; i < r; ++i)
    for (j = 0; j < c; ++j) {
      printf("Enter element b%d%d: ", i + 1, j + 1);
      scanf("%d", &B[i][j]);
    }

  // adding two matrices
  for (i = 0; i < r; ++i)
    for (j = 0; j < c; ++j) {
      sum[i][j] = A[i][j] + B[i][j];
    }

  // printing the result
  printf("\nSum of two matrices: \n");
  for (i = 0; i < r; ++i)
  {
    for (j = 0; j < c; ++j) 
    {
      printf("%d   ", sum[i][j]);
    }  
    printf("\n\n");
  }

  return 0;
}
  2. Multiplication of two matrices.
    3. #include<stdio.h>
#include<conio.h>
void main()
{
  int A[50][50],B[50][50],C[50][50],i,j,k,r1,c1,r2,c2,sum=0;
  
  printf("\nInput the rows and columns of first matrix : ");
  scanf("%d %d",&r1,&c1);
  printf("\nInput the rows and columns of second matrix : ");
  scanf("%d %d",&r2,&c2);
  if(c1!=r2){
      printf("Mutiplication of Matrix is not possible.");
      printf("\nColumn of first matrix and row of second matrix must be same.");
  }
  else
      {
       printf("Input elements in the first matrix :\n");
       for(i=0;i<r1;i++)
        {
            for(j=0;j<c1;j++)
            {
	           printf("element - [%d],[%d] : ",i,j);
	           scanf("%d",&A[i][j]);
            }
        }   
       printf("Input elements in the second matrix :\n");
       for(i=0;i<r2;i++)
        {
            for(j=0;j<c2;j++)
            {
	           printf("element - [%d],[%d] : ",i,j);
	           scanf("%d",&B[i][j]);
            }
        }    
 	 printf("\nThe First matrix is :\n");
  		for(i=0;i<r1;i++)
    		{
      		printf("\n");
      		for(j=0;j<c1;j++)
          	printf("%d\t",A[i][j]);
    		}
  
  	printf("\nThe Second matrix is :\n");
  		for(i=0;i<r2;i++)
    		{
      		printf("\n");
      		for(j=0;j<c2;j++)
      		printf("%d\t",B[i][j]);
    		}
//multiplication of matrix
      for(i=0;i<r1;i++)
      {
          for(j=0;j<c2;j++)
          {
           C[i][j]=0;
              for(k=0;k<c1;k++)    
                     {  
                       C[i][j] +=A[i][k]*B[k][j];
                           
                     }
           }
       }
  printf("\nThe multiplication of two matrices is : \n");
  for(i=0;i<r1;i++)
     {
        printf("\n");
        for(j=0;j<c2;j++)
         {
           printf("%d\t",C[i][j]);
         }
     }
  }
printf("\n\n");
}
  3. Sort array elements using bubble sort.
    4. #include<stdio.h>
#include<conio.h>

void main()
{
    int arr1[100];
    int n, i, j, tmp;
	
	
       printf("\n\nsort elements of array in ascending order using bubble sort :\n ");
       printf("----------------------------------------------\n");	

    printf("Input the size of array : ");
    scanf("%d", &n);

       printf("Input %d elements in the array :\n",n);
       for(i=0;i<n;i++)
            {
	      printf("element - %d : ",i);
	      scanf("%d",&arr1[i]);
	    }

    for(i=0; i<n; i++)
    {
        for(j=i+1; j<n; j++)
        {
            if(arr1[j] <arr1[i])
            {
                tmp = arr1[i];
                arr1[i] = arr1[j];
                arr1[j] = tmp;
            }
        }
    }
    printf("\nElements of array in sorted ascending order:\n");
    for(i=0; i<n; i++)
    {
        printf("%d  ", arr1[i]);
    }
	        printf("\n\n");
}
  4. Concatenate two strings without built-in functions.
    5. #include<stdio.h>

int main()
{
  char str1[10],str2[10],str3[10];
  int i=0,j=0;
  printf("\nEnter First String:");
  gets(str1);
  printf("\nEnter Second String:");
  gets(str2);
  while(str1[i]!='\0')
  {
  str3[i]=str1[i];   
  i++;
  }
  while(str2[j]!='\0')
  {
    str3[i]=str2[j];
    j++;
    i++;
  }
  str3[i]='\0';
  printf("\nConcatenated String is %s",str3);
  return 0;
}
  5. Reverse a string using built-in and without built-in string functions.
    6. With using built-infunction
#include<stdio.h>
int main() 
{
   char str[20] ;
   clrscr();
   printf (“enter a string”);
   gets (str);
   strrev (str);
   printf(“reversed string = %s”,str)
   return 0;
}



Without using built-infunction
#include<stdio.h>
int main() 
{
    char str1[20],str2[20],temp;
   int i,j,k,length=0;
   printf("Enter String : ");
   gets(str1);
   for(i=0;str1[i]!='\0';i++)
   {
      length++;
   }
  
   for(j=length-1,k=0;j>=0;j--,k++)
   {
       str2[k]=str1[j];
   }
	str2[k]='\0';
     printf("Reverse of a string is: %s",str2);
    return 0;
}
Exercise 9: Pointers.
  1. Write a C program to find sum of n elements entered by user. To perform this program, allocate memory dynamically using malloc( ) function.
    2. #include<stdio.h>
#include<conio.h>
#include<stdlib.h>
int main()
{
    
    int i, n, sum = 0;
    int *p;

    printf("Enter number of elements : ");
    scanf("%d", &n);
    p = (int *)malloc(n * sizeof(int));
    for (i = 0; i < n; i++)
    {
        printf("Enter element %d : ", (i + 1));
        scanf("%d", p + i);
        sum += *(p + i);

 }
    printf("sum is %d \n", sum);
    free(p);
    return 0;
}
  2. Write a C program to find sum of n elements entered by user. To perform this program, allocate memory dynamically using calloc( ) function. Understand the difference between the above two programs
    3. #include<stdio.h>
#include<conio.h>
#include<stdlib.h>
int main()
{
    
    int i, n, sum = 0;
    int *p;

    printf("Enter number of elements : ");
    scanf("%d", &n);
    p = (int *)calloc(n, sizeof(int));
    for (i = 0; i < n; i++)
    {
        printf("Enter element %d : ", (i + 1));
        scanf("%d", p + i);
        sum += *(p + i);

 }
    printf("sum is %d \n", sum);
    free(p);
    return 0;
}
  3. Write a C program to find sum of n elements entered by user. To perform this program, allocate memory dynamically using realloc( ) function. Understand the difference between the above two programs
    4. #include <stdio.h>
#include <stdlib.h>
int main()
{
    int *ptr, i , n1, n2;
    clrscr();
    printf("Enter size: ");
    scanf("%d", &n1);

    ptr = (int*) malloc(n1 * sizeof(int));

    printf("Addresses of previously allocated memory: ");
    for(i = 0; i < n1; i++)
	 printf("%u\n",ptr + i);

    printf("\nEnter the new size: ");
    scanf("%d", &n2);

    // rellocating the memory
    ptr = realloc(ptr, n2 * sizeof(int));

    printf("Addresses of newly allocated memory: ");
    for(i = 0; i < n2; i++)
	 printf("%u\n", ptr + i);

    free(ptr);

    return 0;
}
Exercise 10: Structures and union.
  1. Write a C program to find the total, average of n students using structures
    2. #include <stdio.h>>

// Define a structure for a student
struct Student {
    char name[50];
    int marks;
};

int main() {
    int i,n, total = 0;
    float average;
    struct Student students[10];
    printf("Enter the number of students: ");
    scanf("%d", &n);

    // Input student names and marks
    for (i = 0; i < n; i++)
     {
	printf("Enter name of student %d: ", i + 1);
	scanf("%s", students[i].name);
	printf("Enter marks of student %d: ", i + 1);
	scanf("%d", &students[i].marks);
	total += students[i].marks;
    }

    // Calculate average
    average = (float)total / n;

    printf("\nStudent Information:\n");
    printf("Name\t\tMarks\n");
    for (i=0;i<n;i++)
    {
	printf("%s\t\t%d\n", students[i].name, students[i].marks);
    }

    printf("\nTotal marks: %d\n", total);
    printf("Average marks: %.2f\n", average);

    return 0;
}
  2. Write a C program to illustrate Union
    3. #include <stdio.h>>

// Define a union for a student
union Student {
    char name[50];
    int marks;
};

int main() {
    int i,n, total = 0;
    float average;
    union Student students[10];
    printf("Enter the number of students: ");
    scanf("%d", &n);

    // Input student names and marks
    for (i = 0; i < n; i++)
     {
	printf("Enter name of student %d: ", i + 1);
	scanf("%s", students[i].name);
    printf("%s\n",students[i].name);
	printf("Enter marks of student %d: ", i + 1);
	scanf("%d", &students[i].marks);
    printf("%d\n",students[i].marks);
	total += students[i].marks;
    }

    // Calculate average
    average = (float)total / n;
    printf("\nTotal marks: %d\n", total);
    printf("Average marks: %.2f\n", average);

    return 0;
}
Exercise 11: Using functions.
  1. Write a C function to calculate NCR value.
    2. #include <stdio.h>>
 
int fact(int a);
 
int main()
{
    int n, r, ncr;
 
    printf("\n Enter the value for N and R \n");
    scanf("%d%d", &n, &r);
    ncr = fact(n) / (fact(r) * fact(n - r));
    printf("\n The value of ncr is: %d", ncr);
}
 
int fact(int a)
{
    int f = 1, i;
    if (a == 0)
    {
        return(f);
    }
    else
    {
        for (i = 1; i <= a; i++)
	{
            f = f * i;
	}
    }
    return(f);
}
  2. Write a C function to find the length of a string.
    3. #include <stdio.h>>
int length(char str[]);
int main()
{
    char str[100];
    int i;
	
    printf("Enter a string: ");
    scanf("%s", str);
	printf("The length of the string is: %d\n", length(str));
 return 0;   
}
int length(char str[])
{
	int i,l = 0;
    for (i = 0; str[i] != '\0'; i++)
    {
        l++;
    }

    return l;
}
  3. Write a C function to transpose of a matrix.
    4. #include <stdio.h>>
void transpose(int A[10][10], int r, int c, int B[10][10])     
{
    for(int i=0;i<r;i++)     
    {
        for(int j=0;j<c;j++)
        {
            B[j][i]=A[i][j];     
        }
    }
    printf("\nAfter transpose the elements are...\n");
    for(int i=0;i<c;i++)      
    {
        for(int j=0;j<r;j++)
        {
            printf("%d ",B[i][j]);
        }
        printf("\n");
    }
}
int main()
{
    int r,c,A[10][10],B[10][10];                 
    printf("Enter the number of rows and column: \n");
    scanf("%d %d",&r,&c);      
    printf("\nEnter the elements of the matrix: \n");
    for(int i=0;i<r;i++)    
    {
        for(int j=0;j<c;j++)
        {
            scanf("%d",&A[i][j]);
        }
    }
    transpose(A,r,c,B);
    return 0;
}
Exercise 12: Using Recursion Function.
  1. Write a recursive function to generate Fibonacci series.
    2. #include <stdio.h>>

int fibonacci(int num)
{
    if (num == 0)
    {
        return 0; 
    }
    else if (num == 1)
    {
        return 1; 
    }
    else
    {
       return fibonacci(num-1) + fibonacci(num-2); 
    }
}

int main()
{
    int num; 
    printf("Enter the number of elements to be in the series : ");
    scanf("%d", &num); 
    int i;
    for (i = 0; i < num; i++)
    {
        printf("%d,",fibonacci(i)); 
    }

    return 0;
}
  2. Write a recursive function to find the LCM of two numbers.
    3. #include <stdio.h>>
int lcmCalculate(int a, int b);
 
int main()
{
    int n1, n2, lcmOf;
	printf("\n\n Recursion : Find the LCM of two numbers :\n");
	printf("----------------------------------------------\n");
    printf(" Input 1st number for LCM : ");
    scanf("%d", &n1);
    printf(" Input 2nd number for LCM : ");
    scanf("%d", &n2);
    if(n1 >  n2)
        lcmOf = lcmCalculate(n2, n1);
    else
        lcmOf = lcmCalculate(n1, n2);
    printf(" The LCM of %d and %d :  %d\n\n", n1, n2, lcmOf);
    return 0;
}
int lcmCalculate(int a, int b)
{
    static int m = 0;
    m += b;
    if((m % a == 0) && (m % b == 0))
    {
        return m;
    }
    else
    {
        lcmCalculate(a, b);
    }
}
  3. Write a recursive function to find the factorial of a number.
    4. #include <stdio.h>>
long int fact(int n);
int main() {
    int n;
    printf("Enter a positive integer: ");
    scanf("%d",&n);
    printf("Factorial of %d = %ld", n, fact(n));
    return 0;
}

long int fact(int n) 
{
    if (n>=1)
        return n*fact(n-1);
    else
        return 1;
}
Exercise 13: Simple functions using Call by reference, Dangling pointers.
  1. Write a C program to swap two numbers using call by reference.
    2.   #include <stdio.h>>
    void swap(int *, int *);    
    int main()  
    {  
        int a = 10;  
        int b = 20;   
        printf("Before swapping the values in main a = %d, b = %d\n",a,b); 
        swap(&a,&b);  
        printf("After swapping values in main a = %d, b = %d\n",a,b); 
    }  
    void swap (int *a, int *b)  
    {  
        int temp;   
        temp = *a;  
        *a=*b;  
        *b=temp;  
        printf("After swapping values in function a = %d, b = %d\n",*a,*b); 
    }
  2. Demonstrate Dangling pointer problem using a C program.
    3. #include <stdio.h>
#include <stdlib.h>

int main() {
    int *ptr;
    
	ptr = (int *)malloc(sizeof(int)); 

    *ptr = 10;
// memory block deallocated using free() function
    free(ptr);
    
// here ptr acts as a dangling pointer
    printf("%d", *ptr);
    
    // prints garbage value in the output console

    return 0;
}
  3. Write a C program to copy one string into another using pointer.
    4. #include <stdio.h>

void copy_string(char*, char*);

main()
{
    char source[100], target[100];    
    printf("Enter source string\n");    
    gets(source);    
    copy_string(target, source);    
    printf("Target string is \"%s\"\n", target);    
    return 0;
}

void copy_string(char *target, char *source)
{
    while(*source)
    {
        *target = *source;        
        source++;        
        target++;
    }    
    *target = '\0';
}
  4. Write a C program to find no of lowercase, upper case, digits and other characters using pointers.
    5. #include <stdio.h>
void stringcount(char *str)
{
int i,upper=0,lower=0,digits=0,specialchars=0;
for(i=0;str[i];i++)  
{
if(str[i]>='A' && str[i]<='Z')
	upper++;
else if(str[i]>='a' && str[i]<='z') 
	lower++;
else if(str[i]>=48 && str[i]<=57)
    digits++;
else
    specialchars++;
}
printf("Upper case letters = %d\n",upper);
printf("Lower case letters = %d\n",lower);
printf("Digits = %d\n",digits);
printf("Special characters = %d", specialchars);
}

int main()
{
char s[100];  

printf("Enter  the string: ");
gets(s);
    
stringcount(s);
}
Exercise 14: File handling
  1. Write a C program to write and read text in to a file.
    2. #include <stdio.h>
#include <stdlib.h>

int main()
{
   char str[100];
   FILE *fptr;

   fptr = fopen("999.txt","w");

   if(fptr == NULL)
   {
      printf("Error!");   
      exit(1);             
   }

   printf("Entered data is: ");
   gets(str);

   fprintf(fptr,"%s",str);
   
   
   if ((fptr = fopen("999.txt","r")) == NULL){
       printf("Error! opening file");

       exit(1);
   }

   fscanf(fptr,"%s", str);

   printf("data avilable in ext file is n=%s", str);
   fclose(fptr);

   return 0;
}
  2. Copy the contents of one file to another file.
    3. #include <stdio.h>
#include <stdlib.h> // For exit() 

int main() 
{ 
	FILE *fptr1, *fptr2; 
	char filename[100], c; 

	printf("Enter the filename to open for reading \n"); 
	scanf("%s", filename); 

	// Open one file for reading 
	fptr1 = fopen(filename, "r"); 
	if (fptr1 == NULL) 
	{ 
		printf("Cannot open file %s \n", filename); 
		exit(0); 
	} 

	printf("Enter the filename to open for writing \n"); 
	scanf("%s", filename); 

	// Open another file for writing 
	fptr2 = fopen(filename, "w"); 
	if (fptr2 == NULL) 
	{ 
		printf("Cannot open file %s \n", filename); 
		exit(0); 
	} 

	// Read contents from file 
	c = fgetc(fptr1); 
	while (c != EOF) 
	{ 
		fputc(c, fptr2); 
		c = fgetc(fptr1); 
	} 

	printf("\nContents copied to %s", filename); 

	fclose(fptr1); 
	fclose(fptr2); 
	return 0; 
}
  3. Find no. of lines, words and characters in a file.
    4. #include <stdio.h>
#include <stdlib.h>

int main() 
{ 
    FILE *fptr; 
    char ch; 
    int wrd=0,charctr=0,line=0;
    char fname[100];
    printf("\n\n Count the number of words, characters and lines in a file :\n");
	printf("---------------------------------------------------------\n"); 
	printf(" Input the filename to be opened : ");
	scanf("%s",fname);    

    fptr=fopen(fname,"r"); 
    if(fptr==NULL) 
     { 
         printf(" File does not exist or can not be opened."); 
      } 
    else 
        { 
          ch=fgetc(fptr); 
          //printf(" The content of the file %s are : ",fname); 
          while(ch!=EOF) 
            { 
                printf("%c",ch); 
                if(ch==' '||ch=='\n')
                    { 
                        wrd++; 
                        if(ch=='\n')
                        line++;
                    }
                    else
                    {
                        charctr++; 
                    }
                ch=fgetc(fptr); 
            }
        printf("\n The number of words in the  file %s are : %d\n",fname,wrd); 
        printf(" The number of characters in the  file %s are : %d\n",fname,charctr);  
		printf(" The number of lines in the  file %s are : %d\n",fname,line);        
        } 
    fclose(fptr); 
}

All The Best

at

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netaji gandi Saturday, July 12, 2025
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Mr. G. Netaji: VR23 C LAB SOLUTIONS ...