simple question im not sure about

I have a simple function and string:

Code:

---

std::string test = "some string data...";
some_func(test);

void some_func(std::string test) {
}

void some_func(std::string &test) {
}

---

In the first case, the string will be copied when passed to function, and in the second case it will pass the reference (it wont copy the data)?

Am I correct?

Yes. As a replacement for your first function example, you could consider:

Code:

---

void some_func(const std::string& test) {
}

---

So the string is not copied, but at the same time the caller is assured that the string passed will not be modified.

the first case : the compiler will call the copy-constructor to construct a temp string which the value is the same as the test, and when the function ends, the compiler will call the destructor
to destory the temp string

the second case is only passed a reference, and none of the constructor and destructor will be called. because existing a const, you can't modify the test value