The code to find upper and lower diagonal of 3x3 matrices Code: #include<conio.h> #include<stdio.h> void main() { int a[3][3],i,j,k; clrscr(); printf("\n Enter a Matrix 3x3:\n\n"); for(i=0;i<=2;i++) { for(j=0;j<=2;j++) { scanf("%d",&a[i][j]); } } /* Displaying entered matrix 3x3*/ printf("\n The Matrix is:-\n"); for(i=0;i<=2;i++) { for(j=0;j<=2;j++) { printf("%d\t",a[i][j]); } printf("\n"); } printf("\n"); printf("\n Lower diagonal:\n\n"); for(i=1;i<=2;i++) { for(j=0;j<i;j++) { printf("%d\t",a[i][j]); } printf("\n"); } printf("\n \n"); printf("\n Upper diagonal\n"); for(i=0;i<2;i++) { for(j=i+1;j<=2;j++) { if(i==1) { printf(" "); printf("%d",a[i][j]); } else printf("%d\t",a[i][j]); } printf("\n"); } getch(); }