I'm having some trouble with my C code and I keep having the same error repeatedly.. Any help would be great..?

Question

I keep having the same repeated error of "Segmentation Fault" at the end of running the program.

My code is as follows:

#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

#include <math.h>

#include <string.h>

main ()

{

int i, n = 0;

char *x[10];

printf("Enter each string on a separate line below\n\n");

printf("Type \'END\' when finished\n\n");

do {

x[n] = (char *) malloc(12 * sizeof(char));

printf("string %d: ", n + 1);

scanf("%s", x[n]);

}

while (strcmp(x[n++], "END"));

/* reorder the list of strings */

reorder(--n, x);

/* display the reordered list of strings */

printf("\n\nReordered List of STrings:\n");

for (i = 0; i < n; ++i)

printf("\nstring %d: %s", i + 1,x[i]);

}

void reorder(int n, char *x[])

{

char *temp;

int i, item;

for (item = 0; item < n - 1; ++item)

for (i = item + 1; i < n; ++i)

if (strcmp(x[item], x[i]) > 0) {

temp = x[item];

x[item] = x[i];

x[i] = temp;

}

return;

}

cja · Accepted Answer

You have three dangerous things happening here. 1) you're only allocating 12 bytes for each character array pointed to by elements of x[ ], 2) you're are taking whatever is entered by the user and letting scanf store it at x[n], even if the entered string is > 12 characters, and 3) you've declared x[ ] to be of length 10, but you're not limiting the user to entering a max of 10 strings. Any of these put you at risk of referencing unallocated memory, leading to your seg fault.

Anonymous · Answer

Since you've got return at the end of main, main needs to return a type, which means you should have declaired it like:

int main()
(but usually, if not specified defaults to int any way. Do you compile with the -Wall switch?)

Also, you need a function prototype declaration for the reorder() function so it shows this program has a function called reorder() and that it recieves an int and a char like:

void reorder(int, char**);

(Put this under your header declarations, before main)

****** EDIT ******

I got your program working and I Like It!!!
How long have you been programming in C? It's good.

P.S. cja - thanks for the thumbs down BUT I got it working.

I couldn't have been that far off the money if I got it working!!! Could I?

Bill · Answer

If adding the return to main() doesn't help, I'm afraid you've got some work ahead of you.
SegFault is a very vague error, but basically it means you're pointing to a nonexistent memory at some point.

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I'm having some trouble with my C code and I keep having the same error repeatedly.. Any help would be great..?

3 Answers