Please can anyone tell me where am i going wrong in this code?

Question

#include <stdio.h>
#include <stdlib.h>

void readMatrix(int m[10][10],int rows,int columns)
{
int i,j;
for(i=0;i<rows;i++)
{
for(j=0;j<columns;j++)
{
printf("Enter the element matrix %d%d ",i+1,j+1);
scanf(" %d",&m[i][j]);
}
printf("\n");
}
}
void printMatrix(int m[10][10],int rows,int columns)
{
int i,j;
for(i=0;i<rows;i++)
{
for(j=0;j<columns;j++)
{
printf(" %d\t", m[i][j]);
}
printf("\n");
}
}
int main()
{
int i,j,r1,r2,c1,c2;
int sum,k;
int a[10][10],b[10][10],result[10][10];

printf("Enter the number of rows and columns in matrix A:\n");
scanf(" %d %d",&r1,&c1);
readMatrix(a,r1,c1);
printMatrix(a,r1,c1);

printf("Enter the number of rows and columns in matrix B:\n");
scanf(" %d %d",&r2,&c2);
readMatrix(b,r1,c1);
printMatrix(b,r2,c2);

if(r2==c1)
{

for(i=0;i<r1;i++)
{
for(j=0;j<c2;j++)
{
sum=0;
for(k=0;k<r2;k++){
sum = sum +a[i][k]*b[k][j];
}
}result[i][j] = sum;
}
printf("The product of the matrix is :\n");
printMatrix(result,r1,c2);
}
else
{
printf("The product is not possible.");
}
return 0;
}

Answer 1

While Entering Matrix B.
function readMatrix(a,&r1,&c1); had an error in it should be as follows
readMatrix(a,&r2,&c2);
You need to place

result [i][j]=sum;

Inside second for loop i.e.
for(i=0;i<r1;i++)
{
for(j=0;j<c2;j++)
{
for(k=0;k<r2;k++)
{ sum=sum+a[i][k]*b[k][j] }
result [i][j]=sum;
}
}

Answer 2

put result[i][j]=sum; inside the }bracket😉

Answer 3

compilator must said "variable 'j' is not declarated in this scope."
this is your:
for(i=0;i<r1;i++)
{
for(j=0;j<c2;j++)
{
sum=0;
for(k=0;k<r2;k++)
{
sum = sum +a[i][k]*b[k][j];
}
}
result[i][j] = sum; //here
}
and that must be:
for(i=0;i<r1;i++)
{
for(j=0;j<c2;j++)
{
sum=0;
for(k=0;k<r2;k++)
{
sum = sum +a[i][k]*b[k][j];
}
result[i][j] = sum; //here
}
}