Determining the Length of a String Literal

Question

Given an array of pointers to string literals:

char *textMessages[] = {
    \"Small text message\",
    \"Slightly larger text message\",
    \"A really larg         


        

Answer 1

My suggestion would be to use strlen and turn on compiler optimizations.

For example, with gcc 4.7 on x86:

#include <string.h>
static const char *textMessages[3] = {
    "Small text message",
    "Slightly larger text message",
    "A really large text message that "
    "is spread over multiple lines"
};

size_t longmessagelen(void)
{
  return strlen(textMessages[2]);
}

After running make CFLAGS="-ggdb -O3" example.o:

$ gdb example.o
(gdb) disassemble longmessagelen
   0x00000000 <+0>: mov    $0x3e,%eax
   0x00000005 <+5>: ret

I.e. the compiler has replaced the call to strlen with the constant value 0x3e = 62.

Don't waste time performing optimizations that the compiler can do for you!