c++ - Difference between passing array, fixed-sized array and base address of array as a function parameter

Question

I am confused about which syntax to use if I want to pass an array of known or unknown size as a function parameter.

Suppose I have these variants for the purpose:

void func1(char* str) {
    //print str
}

void func2(char str[]) {
    //print str
}

void func3(char str[10]) {
    //print str
}

What are the pros and cons of using each one of these?

Answer 1

All these variants are the same. C just lets you use alternative spellings but even the last variant explicitly annotated with an array size decays to a normal pointer.

That is, even with the last implementation you could call the function with an array of any size:

void func3(char str[10]) { }

func("test"); // Works.
func("let's try something longer"); // Not a single f*ck given.

Needless to say this should not be used: it might give the user a false sense of security (“oh, this function only accepts an array of length 10 so I don’t need to check the length myself”).

As Henrik said, the correct way in C++ is to use std::string, std::string& or std::string const& (depending on whether you need to modify the object, and whether you want to copy).