Case Insensitive String Comparison in C

Question

I have two postcodes char* that I want to compare, ignoring case. Is there a function to do this?

Or do I have to loop through each use the tolower function and then do the comparison?

Any idea how this function will react with numbers in the string

Thanks

Answer 1

There is no function that does this in the C standard. Unix systems that comply with POSIX are required to have strcasecmp in the header strings.h; Microsoft systems have stricmp. To be on the portable side, write your own:

int strcicmp(char const *a, char const *b) {     for (;; a++, b++) {         int d = tolower((unsigned char)*a) - tolower((unsigned char)*b);         if (d != 0 || !*a)             return d;     } } 

But note that none of these solutions will work with UTF-8 strings, only ASCII ones.

Answer 2

Take a look at strcasecmp() in strings.h.