Differences between single-quotes and double-quotes in C

Question

Recentely I have seen that if I use printf with \'foo\' I get a warning.

printf(\'numero\');

warning: character con

Answer 1

'' is used to denote characters while "" is used to denote strings.

printf expects a const char*(a string) as its first argument. You need to use "" for that. If you use '', the compiler will complain and will tell you that printf expects a const char* as its first argument and not a char.

FYI, adding more than one character into '' (like 'numero') will make a multi-character literal whose value is implementation defined.