Can someone explain how this works?

Question

Sorting string into alphabetical order
but im a little bit confused on how this exactly works
why do we need to use a pointer (&str)?
im a lil bit confused for pointers hehe
also is there an easier way to do this?

code:
#include<bits/stdc++.h>
using namespace std;

void sortString(string &str)
{
sort(str.begin(), str.end());
cout << str;
}

int main()
{
string s;
cin>>s;
sortString(s);
return 0;
}

Answer 1

Mirielle,

Close but not 100% correct...

"When a function takes a parameter by reference, it receives a pointer to the memory location of the variable, rather than a copy of the variable itself."

The function doesn't receive a pointer it receives a reference. There is a difference between passing by reference and by pointer. Mainly that you cannot change a reference, whereas you can change a standard pointer (excluding special pointer types).

Quick example in the code below, this is passing a pointer to the function:

#include<bits/stdc++.h>
using namespace std;

void passBy(string *str)
{
string nstr {"new string"};
str = &nstr;

cout << *str;
}

// Will not work.
//void passBy(string &str)
//{
// string nstr {"new string"};
// str = &nstr;
//
// cout << *str;
//}

int main() {
string * sptr = nullptr;
string str {"test string"};

sptr = &str;

passBy(str);

return 0;
}

The pointer can be changed to point to whatever you need, however if you uncomment the reference function (it won't even compile). That's because it passes a reference to the function, which can not be modified (it's not a pointer).