Question:String concatenation in c without using string functions 

#include<stdio.h>

void stringConcat(char[],char[]);
int main(){

    char str1[100],str2[100];
    int compare;

    printf("Enter first string: ");
    scanf("%s",str1);

    printf("Enter second string: ");
    scanf("%s",str2);

    stringConcat(str1,str2);

    printf("String after concatenation: %s",str1);

    return 0;
}

void stringConcat(char str1[],char str2[]){
    int i=0,j=0;
   
   
    while(str1[i]!='\0'){
         i++;
    }

    while(str2[j]!='\0'){
         str1[i] = str2[j];   
         i++;
         j++;
    }

    str1[i] = '\0';
}
Sample output:
Enter first string: cquestionbank
Enter second string: @blogspot.com
String after concatenation: cquestionbank@blogspot.com

Question:C program to compare two strings without using string functions 

#include<stdio.h>

int stringCompare(char[],char[]);
int main(){

    char str1[100],str2[100];
    int compare;

    printf("Enter first string: ");
    scanf("%s",str1);

    printf("Enter second string: ");
    scanf("%s",str2);

    compare = stringCompare(str1,str2);

    if(compare == 1)
         printf("Both strings are equal.");
    else
         printf("Both strings are not equal");
 
    return 0;
}

int stringCompare(char str1[],char str2[]){
    int i=0,flag=0;
   
    while(str1[i]!='\0' && str2[i]!='\0'){
         if(str1[i]!=str2[i]){
             flag=1;
             break;
         }
         i++;
    }

    if (flag==0 && str1[i]=='\0' && str2[i]=='\0')
         return 1;
    else
         return 0;

}
Sample output:
Enter first string: cquestionbank.blogspot.com
Enter second string: cquestionbank.blogspot.com
Both strings are equal.

Question:String copy without using strcpy in c programming language 

#include<stdio.h>

void stringCopy(char[],char[]);

int main(){

    char str1[100],str2[100];

    printf("Enter any string: ");
    scanf("%s",str1);

    stringCopy(str1,str2);

    printf("After copying: %s",str2);
 
    return 0;
}

void stringCopy(char str1[],char str2[]){
    int i=0;

    while(str1[i]!='\0'){
         str2[i] = str1[i];
         i++;
    }

    str2[i]='\0';
}
Sample output:
Enter any string: cquestionbank.blogspot.com
After copying: cquestionbank.blogspot.com

Question:Program to convert string into ASCII values in c programming language 

#include<stdio.h>

int main(){
  
    char str[100];
    int i=0;

    printf("Enter any string: ");
    scanf("%s",str);

    printf("ASCII values of each characters of given string: ");
    while(str[i])
         printf("%d ",str[i++]);
        
   
    return 0;
}
Sample Output:
Enter any string: cquestionbank.blogspot.com
ASCII values of each characters of given string: 99 113 117 101 115 116 105 111 110 98 97 110 107 46 98 108 111 103 115 112 111 116 46 99 111 109

Question:C program for addition of two matrices using arrays source code. 

#include<stdio.h>
int main(){
  int a[3][3],b[3][3],c[3][3],i,j;
  printf("Enter the First matrix->");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&a[i][j]);
  printf("\nEnter the Second matrix->");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&b[i][j]);
  printf("\nThe First matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           printf("%d\t",a[i][j]);
  }
  printf("\nThe Second matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
      printf("%d\t",b[i][j]);
   }
   for(i=0;i<3;i++)
       for(j=0;j<3;j++)
            c[i][j]=a[i][j]+b[i][j];
   printf("\nThe Addition of two matrix is\n");
   for(i=0;i<3;i++){
       printf("\n");
       for(j=0;j<3;j++)
            printf("%d\t",c[i][j]);
   }
   return 0;
}

Question:SUBTRACTION OF TWO MATRICES USING C PROGRAM 

#include<stdio.h>
int main(){
  int a[3][3],b[3][3],c[3][3],i,j;
  printf("Enter the First matrix->");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&a[i][j]);
  printf("\nEnter the Second matrix->");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&b[i][j]);
  printf("\nThe First matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           printf("%d\t",a[i][j]);
  }
  printf("\nThe Second matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
      printf("%d\t",b[i][j]);
   }
   for(i=0;i<3;i++)
       for(j=0;j<3;j++)
            c[i][j]=a[i][j]-b[i][j];
   printf("\nThe Subtraction of two matrix is\n");
   for(i=0;i<3;i++){
       printf("\n");
       for(j=0;j<3;j++)
            printf("%d\t",c[i][j]);
   }
   return 0;
}

Question:Write a program for matrix multiplication in c 

#include<stdio.h>
int main(){
  int a[5][5],b[5][5],c[5][5],i,j,k,sum=0,m,n,o,p;
  printf("\nEnter the row and column of first matrix");
  scanf("%d %d",&m,&n);
  printf("\nEnter the row and column of second matrix");
  scanf("%d %d",&o,&p);
  if(n!=o){
      printf("Matrix mutiplication is not possible");
      printf("\nColumn of first matrix must be same as row of second matrix");
  }
  else{
      printf("\nEnter the First matrix->");
      for(i=0;i<m;i++)
      for(j=0;j<n;j++)
           scanf("%d",&a[i][j]);
      printf("\nEnter the Second matrix->");
      for(i=0;i<o;i++)
      for(j=0;j<p;j++)
           scanf("%d",&b[i][j]);
      printf("\nThe First matrix is\n");
      for(i=0;i<m;i++){
      printf("\n");
      for(j=0;j<n;j++){
           printf("%d\t",a[i][j]);
      }
      }
      printf("\nThe Second matrix is\n");
      for(i=0;i<o;i++){
      printf("\n");
      for(j=0;j<p;j++){
           printf("%d\t",b[i][j]);
      }       
      }
      for(i=0;i<m;i++)
      for(j=0;j<p;j++)
           c[i][j]=0;
      for(i=0;i<m;i++){ //row of first matrix
      for(j=0;j<p;j++){  //column of second matrix
           sum=0;
           for(k=0;k<n;k++)
               sum=sum+a[i][k]*b[k][j];
           c[i][j]=sum;
      }
      }
  }
  printf("\nThe multiplication of two matrix is\n");
  for(i=0;i<m;i++){
      printf("\n");
      for(j=0;j<p;j++){
           printf("%d\t",c[i][j]);
      }
  }
  return 0;
}

Question:Sum of diagonal elements of a matrix in c 

#include<stdio.h>

int main(){

  int a[10][10],i,j,sum=0,m,n;

  printf("\nEnter the row and column of matrix: ");
  scanf("%d %d",&m,&n);

  printf("\nEnter the elements of matrix: ");
  for(i=0;i<m;i++)
      for(j=0;j<n;j++)
           scanf("%d",&a[i][j]);
  printf("\nThe matrix is\n");

  for(i=0;i<m;i++){
      printf("\n");
      for(j=0;j<m;j++){
      printf("%d\t",a[i][j]);
      }
 }
 for(i=0;i<m;i++){
     for(j=0;j<n;j++){
          if(i==j)
              sum=sum+a[i][j];
     }
 }
 printf("\n\nSum of the diagonal elements of a matrix is: %d",sum);

 return 0;
}
Sample output:
Enter the row and column of matrix: 3 3
Enter the elements of matrix: 2
3
5
6
7
9
2
6
7
The matrix is
2       3       5
6       7       9
2       6       7
Sum of the diagonal elements of a matrix is: 16

Question:C program to find transpose of given matrix 

#include<stdio.h>
int main(){
  int a[10][10],b[10][10],i,j,k=0,m,n;
  printf("\nEnter the row and column of matrix");
  scanf("%d %d",&m,&n);
  printf("\nEnter the First matrix->");
  for(i=0;i<m;i++)
      for(j=0;j<n;j++)
           scanf("%d",&a[i][j]);
  printf("\nThe matrix is\n");
  for(i=0;i<m;i++){
      printf("\n");
      for(j=0;j<m;j++){
           printf("%d\t",a[i][j]);
      }
  }
  for(i=0;i<m;i++)
      for(j=0;j<n;j++)
           b[i][j]=0;
  for(i=0;i<m;i++){
      for(j=0;j<n;j++){
           b[i][j]=a[j][i];
           printf("\n%d",b[i][j]);
      }
  }
  printf("\n\nTraspose of a matrix is -> ");
  for(i=0;i<m;i++){
      printf("\n");
      for(j=0;j<m;j++){
           printf("%d\t",b[i][j]);
      }
  }
  return 0;
}

Question:How to find inverse of a matrix in c 

#include<stdio.h>

int main(){

  int a[3][3],i,j;
  float determinant=0;

  printf("Enter the 9 elements of matrix: ");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&a[i][j]);

  printf("\nThe matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           printf("%d\t",a[i][j]);
  }

  for(i=0;i<3;i++)
      determinant = determinant + (a[0][i]*(a[1][(i+1)%3]*a[2][(i+2)%3] - a[1][(i+2)%3]*a[2][(i+1)%3]));

   printf("\nInverse of matrix is: \n\n");
   for(i=0;i<3;i++){
      for(j=0;j<3;j++)
           printf("%.2f\t",((a[(i+1)%3][(j+1)%3] * a[(i+2)%3][(j+2)%3]) - (a[(i+1)%3][(j+2)%3]*a[(i+2)%3][(j+1)%3]))/ determinant);
       printf("\n");
   }

   return 0;
}
Sample Output:
Enter the 9 elements of matrix: 3
5
2
1
5
8
3
9
2

The matrix is

3       5       2
1       5       8
3       9       2
Inverse of matrix is:

0.70    -0.25   0.07
-0.09   -0.00   0.14
-0.34   0.25    -0.11