use of strtof()

[MK27]

I was going to help this person, and in the course of writing a short demo realized I had not used strtof before and to my horror, am suddenly dumbfounded.

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

int main() {
        float X;
        const char fnum[]="13.666";

        X=strtof(fnum,NULL);
        perror("strtof");
        printf("%s\n%f\n",(char*)fnum,X);

        return 0;
}

Which on my system yields:

strtof: Success
13.666
1096460288.000000

Where's the catch???

[bithub]

I'm guessing you are using gcc. If you compile that with gcc -Wall it will say something like: "Warning implicit declaration of strtof". If you compile with gcc -std=c99, the function will start working. strtof is c99 only.

[Maz]

If you compile with -Wall, do you get warning about implicit declaation? It may be that strtof() is not in stdlib.h
=> compiler expects it to return an int, and things get messy. (I do not know though, just guessing )

Also strtof() came with c99 if I'm not wrong, perhaps you should have some compiler flags turned on?

[MK27]

Thanks people. I usually use -Wall, and according to GNU strtof() is in stdlib.h. They are correct; the reason for that warning (AFAIK) is to remind you that the function is non-standard. If you're writing stuff for a gnu system and want out of the warning, you can include the prototype for the function and gcc will shut up.

-std=c99 did it. I guess I have to finish my other post now...