CODEWITHSUNDEEP
c
Tanveesh Singh
Tanveesh Singh

Reputation: 15

Matrix multiplication program

The code below shows segmentation error.
The error prevails
Tried many changes but of no use

#include<conio.h>
#include<stdio.h>
void main()
{
  static int a[100][100],b[100][100],c[100][100]={0};
  int m,n,p,i,j,k;
  printf("Enter no pf rows and colums for matrix A");
  scanf("%d%d",&m,&n);
  for(i=0;i<=m-1;i++)
  {
    for(j=0;j<=n-1;j++)
    {
      printf("enter no.");
      scanf("%d",&a[i][j]);
    }
  }
  printf("Enter no. of column for matrix b");
  scanf("%d",&p);
  for(i=0;i<=n-1;i++)
  {
    for(j=0;j<=p-1;j++)
    {
      printf("enter no.");
      scanf("%d",&b[i][j]);
    }
  }
  for(i=0;i<=m-1;i++)
  {
    for(j=0;i<=p-1;j++)
    {
      c[i][j]=0;
      for(k=0;k<=n-1;k++)
      {
        c[i][j]=c[i][j]+a[i][k]*b[k][j];
      }
    }
  }
  printf(" The resultant matrix is");
  for(i=0;i<=m-1;i++)
  {
    for(j=0;j<=p-1;j++)
    {
      printf("%d\t",c[i][j]);
    }
  printf("\n");
  }

getch();
}

Tried it on turbo c++

Error 139 Segmentation error

Upvotes: 0

Views: 50

Answers (1)

bruno
bruno

Reputation: 32586

Error 139 Segmentation error

this is because

     for(j=0;i<=p-1;j++)

must be

    for(j=0;j<=p-1;j++)

currently j is increased without end so c[i][j]=0; and other accesses are out of the array with an undefined behavior (your segmentation fault)

Other remarks :

  • to do for(j=0; j < p; j++) is a better choice compatible with for instance size_t with is the right type for an index

  • I strongly encourage you to check if your scanf success, currently you do not know if valid numbers was enter, for instance

    if (scanf("%d%d",&m,&n)!= 2)
  fprintf(stderr, "invalid numbers");
else {

  • also check when necessary the enter values are > 0, this must be the case for the number of rows and columns

Upvotes: 2

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