Since I can't return a local variable, what's the best way to return a string from a C or C++ function?

Question

As a follow-up to this question:

From what I\'ve seen, this should work as expected:

void greet(){
  char c[] = \"Hello\";
  greetWith(c);
  return;
         


        

Answer 1

If you need to do this in C++, using std::string as suggested by Greg Hewgill is definitely the most simple and maintainable strategy.

If you are using C, you might consider returning a pointer to space that has been dynamically allocated with malloc() as suggested by Jesse Pepper; but another way that can avoid dynamic allocation is to have greet() take a char * parameter and write its output there:

void greet(char *buf, int size) {
    char c[] = "Hello";

    if (strlen(c) + 1 > size) {
        printf("Buffer size too small!");
        exit(1);
    }

    strcpy(buf, c);
}

The size parameter is there for safety's sake, to help prevent buffer overruns. If you knew exactly how long the string was going to be, it would not be necessary.