What does & mean while passing string or vector to function?

Question

what is the purpose of using & while passing string or vector to a function by reference like this

int function(string & x){
return 0;
}

or

int function(vector<int>&x){
return 0;
}

why it shows error while using *.

Any [decent book](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list), tutorial or class should have taught you about *references*. — Some programmer dude, Mar 01 '21 at 09:05
`why it shows error while using *`, what do you mean, what error? — anastaciu, Mar 01 '21 at 09:06
As for the error when using `*`, here you need to learn more about *pointers* and how they work. — Some programmer dude, Mar 01 '21 at 09:16

score 2 · Answer 1 · answered Mar 01 '21 at 09:07

2

When you pass reference with & ,you pass the actual data rather than passing a copy of data . Change you do in the vector is done on actual vector.

answered Mar 01 '21 at 09:07

Harsh Chaturvedi

679
6
13

score 0 · Answer 2 · answered Mar 01 '21 at 09:36

Passing by reference i.e. using the & means you get access to the actual instance you passed to the function, in your case the vector or the string. Changes to the variable inside the function will also reflect outside the scope of your function.

thus,

#include <iostream>

int function(std::string & x) {
  x = "Hello Function!";
  return 0;
}

int main() {
  std::string my_string("Hello World!");
  function(my_string);                 // Pass by reference
  std::cout << my_string << std::endl; // Will print "Hello Function"
  return 0;
}

What does & mean while passing string or vector to function?

2 Answers2