strcasestr not working properly

Question

I have two struct arrays and a nested for loop. There are words that are identical in the two arrays, but strcasestr is not detecting them. I used strcasestr to also find substrings within words that are identical.

Here's a snippet of my code:

for(int itr = 0; itr < arrayItr; itr++)
{
    for(int itr2 = 0; itr2 < arrayItr2; itr2++)
    {
        if(strcasestr(termsArraypast[itr].term, termsArrayTerms[itr2].term) > 0)
        {
            printf("%d %d %s\n", termsArraypast[itr].charDistance, termsArraypast[itr].termDistance, termsArraypast[itr].term);
        }
    }
}

Please know that all of these variables have already been declared in my program. I've just been on this portion for hours and can't figure it out. Thanks.

The condition is wrong. The `strcasestr` function returns a pointer to the beginning of the substring, or `NULL` if the string is not found. Whole technically non-null is larger than zero, you should still compare against `NULL`. — Some programmer dude, Nov 05 '13 at 05:56
As for the problem, what are the contents of the two strings you pass to the function? — Some programmer dude, Nov 05 '13 at 05:56

Knight71 · Answer 1 · 2013-11-05T07:09:38.953

char *strcasestr(const char *haystack, const char *needle);

return a pointer to the beginning of the substring or null if the string is not found

So it will return a pointer value not an integer which may be outside of integer range.

And you are comparing it with greater than 0 . That is wrong , You could just check for not zero.

eg: program

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

  int main()
  {
char arr1[10];
char arr2[10];
int ret;
strcpy(arr1,"foobar");
strcpy(arr2,"foobar");
printf("arr1 %s\n",arr1);
printf("arr2 %s\n",arr2);

ret= strcasestr(arr1,arr2) ;

printf("ret %d ret %p \n",ret,ret);
if(strcasestr(arr1,arr2) >0)
{
    printf("sub found\n");
}
    if(strcasestr(arr1,arr2) != 0)
     printf("substring found for not null check \n" );      
 }

o/p

arr1 foobar
arr2 foobar
ret -1073787886 ret 0xbfff4c12 
substring found for not null check

strcasestr not working properly

1 Answers1