Questions

#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

It is the FUTURE, which is infront of us but we cannot see.

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

Passivity of iron is due to formation of an extremely thin and impervious film of ferrosoferric oxide Fe3O4on the surface of iron. Chromic acid, being a powerful oxidising agent (like nitric acid ) renders iron passive. 

In scouts, the military and most outdoor books or schools teach the COLDER principal. It is a great acronym for caring and using you clothing.

C - keep your clothing CLEAN. Dirt can break down the fibers of your clothing.

O - don't OVERHEAT. Sweat can lessen the effectiveness of clothing.

L - wear you clothes LOOSE and in LAYERS. Makes your system versatile.

D - stay DRY.

E - EXAMINE your clothing. Look for worn or damaged areas of you clothing.

R - REPAIR any damage that is found.