# Multiplying two 3x3 Matrix Using User Defined Function and Displaying Result from Main Function

``````
#include<stdio.h>
#include<conio.h>

/* Function Prototype */
void multiply(int a[3][3], int b[3][3], int m[3][3]);

int main()
{
int a[3][3], b[3][3], m[3][3],i,j;
clrscr();
/* Reading First Matrix a */
printf("Enter First Matrix:\n");
for(i=0;i< 3;i++)
{
for(j=0;j< 3;j++)
{
printf("a[%d][%d]=",i,j);
scanf("%d", &a[i][j]);
}
}
/* Reading Second Matrix b */
printf("Enter Second Matrix:\n");
for(i=0;i< 3;i++)
{
for(j=0;j< 3;j++)
{
printf("b[%d][%d]=",i,j);
scanf("%d", &b[i][j]);
}
}
/* Function Call */
multiply(a,b,m);
/* Keep in mind that m is empty array.
We will multiply a and b matrix in user
defined function and resultant matrix will
be stored in m and after function call we can
access resultant matrix from main function
since change in array from user defined
function are automatically reflected back
in main function */
/* Displaying Resultant Matrix m */
printf("Enter First Matrix:\n");
for(i=0;i< 3;i++)
{
for(j=0;j< 3;j++)
{
printf("%d\t", m[i][j]);
}
printf("\n");
}
getch();
return 0;
}
/* Function Definition */
void multiply(int a[3][3], int b[3][3], int m[3][3])
{
int i,j,k;
/* Multiplication */
for(i=0;i< 3;i++)
{
for(j=0;j< 3;j++)
{
m[i][j]=0;
for(k=0;k< 3;k++)
{
m[i][j] +=a[i][k] * b[k][j];
}
}
}
}
``````