Can I get best performance making static variables?

Question

Why some people do:

char baa(int x) {
    static char foo[] = \" .. \";
    return foo[x ..];
}

instead of:

char baa(int x) {
          


        

Answer 1

In typical implementations, the version with static will just put the string somewhere in memory at compile time, whereas the version without static will make the function (each time it's called) allocate some space on the stack and write the string into that space.

The version with static, therefore,

• is likely to be quicker
• may use less memory
• will use less stack space (which on some systems is a scarce resource)
• will play nicer with the cache (which isn't likely to be a big deal for a small string, but might be if foo is something bigger).