Thread: strcmp return value

does strcmp always return 0, 1 (or -1) for equal, greater (or the opposite) respectively?

Yes...

If the two strings are equal it will return 0.
If the first string is alphabetically earlier (less than) the second, it will return -1
If the first string is alphabetically later (greater than) than the second it will return 1

Originally Posted by CommonTater

Yes...

If the two strings are equal it will return 0.
If the first string is alphabetically earlier (less than) the second, it will return -1
If the first string is alphabetically later (greater than) than the second it will return 1

but why does the strcmp manual only mention that it will be zero if the strings are equal, greater than zero, or less than zero?

Originally Posted by cph

but why does the strcmp manual only mention that it will be zero if the strings are equal, greater than zero, or less than zero?

Because CommonTater is mistaken. (I feel as though I remember getting numbers larger than 1, but I don't have an example on me.)

Originally Posted by tabstop

Because CommonTater is mistaken. (I feel as though I remember getting numbers larger than 1, but I don't have an example on me.)

Ummm... come to think of it... I am wrong... the relationships are right but yes, it will return higher or lower values...

Thanks.

It may be implementation dependent...
My best suggestion is to test it with your library....

Code:

char a[4] = "aaa";
char e[4] = "eee";
int x;
x = strcmp(a,a);
printf("%d\n",x);
x = strcmp(a,e);
printf("%d\n",x);
x = strcmp(e,a);
printf("%d\n",x);

When in doubt... check it out!

Originally Posted by zacs7

Or, when in doubt, don't make assumptions...

Ever noticed how the little piggie that takes sloppy seconds never gets the best milk?

I have found that the returned value is most likely the numeric difference between the chars that were not equal. There is really no reason why a speedy program would want to convert a positive/negative value to +1 and -1 respectively when it already meets the documented criteria.

does the result depend on the compiler?
this code gave the same result on my PC (compiled with msvc & gcc)

Code:

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

int main (void)
{
    const char *str[2] = { "eeny meeny miny mo",
                           "function calls are so damn slow" };

    printf("result: %d\n", strcmp(str[1], str[0]));

    return(0);
}

output:

Code:

result: 1

I said....

If the two strings are equal it will return 0.
If the first string is alphabetically earlier (less than) the second, it will return -1
If the first string is alphabetically later (greater than) than the second it will return 1

Tabstop says...

Because CommonTater is mistaken. (I feel as though I remember getting numbers larger than 1, but I don't have an example on me.)

and later...

So for instance, I get -1, 0, or +1 on my windows machine regardless of whether I'm using minGW or whatever

Ain't it a pain when you get so zealous about correcting people that it comes right back around to bite you....

Originally Posted by CommonTater

I said....


Tabstop says...

and later...


Ain't it a pain when you get so zealous about correcting people that it comes right back around to bite you....

Brilliant use of selective editing there.