Segmentation fault strcmp in c

Question

I'm trying to run a program in c that takes in a text file and string from the user and then searches the file for that string. It keeps getting a segmentation fault and gdb is pointing me towards this function but I am not sure what the problem is. I am pretty sure it has something to do with the strcmp call but I am not sure. Any help with this issue would be greatly appreciated.

int inTable( const char *s )
{
    int i;

    for( i=0; i<numLines; ++i )
    {
        if( strcmp( st[i], s ) == 0 )
                return 1;
    }

    return 0;
}

st is the file that is read in using fgets() – user4959809 Jun 01 '15 at 06:14 — user4959809, Jun 01 '15 at 06:14
@user4959809 , Is `st` a `FILE*`? – Spikatrix Jun 01 '15 at 06:19 — Spikatrix, Jun 01 '15 at 06:19

score 5 · Accepted Answer · answered Jun 01 '15 at 06:28

You should check that you properly use strcmp(), the API is:

int strcmp(const char *str1, const char *str2)

You must:

1) Validate that st[i], your first argument is a pointer.

2) Make sure that st[i] & s has the Null terminator '\0'`.

3) Check that st[i] & s pointing to an allocated place in the memory before calling strcmp().

score 1 · Answer 2 · edited Jul 20 '17 at 05:09

1

I think you should check s:

int inTable(const char *s) 
{
     if (s == NULL)
     {
          return 0;
     }

     // invoke strcmp
}

make sure const char *s is terminated with '\0

edited Jul 20 '17 at 05:09

Noam M

3,156
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answered Jun 01 '15 at 06:12

finesse

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Segmentation fault strcmp in c

2 Answers2