Passing a 2d array with pointers and accessing it gives segmentation fault

Question

im trying to pass a 2D array from main to a function and trying to print it letter by letter but it keeps giving me segmentation fault

note: the question im trying to solve as mentioned a function with parameter { ArrPrintMatrix(char *(p)[7]) } so help me by keeping the above thing in mind

    #include<stdio.h>
ArrPrintMatrix(char **p,int n) {
    int i,j;
    for(i=0;i<n;i++) {
        for(j=0;j<10;j++) {
            printf("%c ",p[i][j]);
        }
    }
}

main() {
    int i;
    char c[2][10];
    puts("enter two strings");
    for(i=0;i<2;i++)
    scanf("%s",c[i]);

    ArrPrintMatrix((char **) c,2);
}

a char[n][m] is not synonymous with char**. Whatever tutorial or book said otherwise... burn it. — WhozCraig
– WhozCraig, Commented Nov 7, 2018 at 15:56
This is pretty unsafe. You've made a 2d array of char, and then you call scanf on a string. This is asking for segfault overruns. And As Whoz said, char[][] is not char**. — Micromuncher
– Micromuncher, Commented Nov 7, 2018 at 16:05

Yunbin Liu · Accepted Answer · 2018-11-07 16:05:43Z

1

You should use char p[2][10] not char** p

The following code could work:

#include <stdio.h>

void ArrPrintMatrix(char p[2][10], int n) {
    int i;
    for (i = 0; i < n; ++i)
        printf("%s\n",p[i]);
}

int main() {
    int i;
    char c[2][10];
    puts("enter two strings");
    for(i=0;i<2;i++)
        scanf("%s",c[i]);

    ArrPrintMatrix(c,2);
    return 0;
}

answered Nov 7, 2018 at 16:05

Yunbin Liu

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Comments

H.cohen · Accepted Answer · 2018-11-08 04:04:05Z

1

you need to change the type of the p var in the print function, and you should also set the array to zero so if the strings that are printing are less than 10 chars with terminator- garbage values are not displayed.

void ArrPrintMatrix(char p[][10],int n) {
int i,j;
for(i=0;i<n;i++) {
    for(j=0;j<10;j++) {
        printf("%c ",p[i][j]);
    }
  }
}

int main() {
 int i;
 char c[2][10]= {0};
 puts("enter two strings");
 for(i=0;i<2;i++)
 scanf("%s",c[i]);

 ArrPrintMatrix( c,2);
 return 0;
 }

edited Nov 8, 2018 at 4:04

answered Nov 7, 2018 at 16:39

H.cohen

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