CODEWITHSUNDEEP
cstringcase-insensitive
user1513475
user1513475

Reputation: 13

Case insensitive comparison of constant strings

I'm trying to use this function to compare two strings, case insensitively.

int strcasecmp(const char *x1, const char *x2);

I have the copy piece correct, yet the case sensitive portion is giving me some trouble as const is a constant, thus read only, making these fail: 

*x1 = (tolower(*x1)); // toupper would suffice as well, I just chose tolower
*x2 = (tolower(*x2)); // likewise here

Both chars must remain const, otherwise I think this would work... So my question: is there a way to ignore capitalization while keeping the char-strings const?

Upvotes: 1

Views: 2558

Answers (2)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726579

Sure - you can compare the results of tolower right in the if statement:

while (*x1 && *x2 && tolower(*x1) == tolower(*x2)) {
    x1++;
    x2++;
}
return tolower(*x1)-tolower(*x2);

Upvotes: 2

hopia
hopia

Reputation: 5006

You could use a temporary char variable:

char c1 = tolower(*x1);
char c2 = tolower(*x2);

if (c1 == c2)
 ...

Upvotes: 2

Related Questions