How do I check if a value matches a string

Question

Major brainfreeze while learning C here.

I have a struct here with something like:

char *sname;
........
players[i].sname

equalling "James".

I need to check for equality between values like so:

if (players[i].sname == 'Lee')

but am not having much luck. Is there a str function I should be using or is there anyway to fix up my if statement. It's not working atm.

Answer 1

You should be using strcmp():

if (strcmp(players[i].sname, "Lee") == 0) { ...

Also note that strings in C are surrounded by double quotes: "". Single characters are surrounded by single quotes: ''. I'm not sure exactly what your compiler might be doing with 'Lee', but it's almost certainly not what you want.

Answer 2

You'd be looking for strcmp() from the header <string.h>.

Answer 3

The short answer: strcmp().

The long answer: So you've got this:

if(players[i].sname == 'Lee')

This is wrong in several respects. First, single-quotes mean "character literal" not "string literal" in C.

Secondly, and more importantly, "string1" == "string2" doesn't compare strings, it compares char *s, or pointers to characters. It will tell you if two strings are stored in the same memory location. That would mean they're equal, but a false result wouldn't mean they're inequal.

strcmp() will basically go through and compare each character in the strings, stopping at the first character that isn't equal, and returning the difference between the two characters (which is why you have to say strcmp() == 0 or !strcmp() for equality).

Note also the functions strncmp() and memcmp(), which are similar to strcmp() but are safer.