Really simple references/char question

Hi, little problem with references, char*s and passing.

To simplify the problem:

Code:

---

#include <iostream.h>

char& foo(char& c, const char& d) {
  cout << c << " " << d << endl;
  c = d;
  return c;
}

main() {
  char* c = "This is a test";
  char* d = "This is also a test"
 
  foo(c,d);

  cout << c;
}

---

This doesn't compile. I could pass foo(*c,*d), but then foo() will only have access to the first character.

Insight?

You could do it like this. Pass the addresses of the strings and the function can use the strings.

Code:

---

char *foo(char *c, char *d) {
  cout << c << " " << d << endl;
  c = d;
  return c;
}

---

I don't suppose there's a way of doing that by using references in the argument list?

To do this the "C++" way you should use std::string instead of char *.

Something like this..

Code:

---

#include <iostream> //DO NOT USE .h headers
#include <string>
using namespace std;


//Note void. No need to return since you are using a reference
void foo(string &c, const string &d)
{
  cout << c << " " << d << endl;
  c = d;
}

int main()
{
  string c = "This is a test";
  string d = "This is also a test";
  foo(c, d);
  cout << c << endl;
  return 0;
}

---

I suppose I was trying to mix to many different styles there. Thanks for the help.

(by the way, I was returning char& so I could say something like cout << foo(a,b);)

Does it really matter if you include the .h?

.h is non standard

Quote:

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but then foo() will only have access to the first character.

---

Well... not true!

Arrays are stored sequentially, so if your function can get-to the first character, it can get to 'em all. If fact, passing a pointer is the most common way of doing this sort of thing. (And the most common way of getting a function to update multiple variables.)

If you're a "newbie", this may not mean much yet, but pointers are also used to pass structures and objects into functions.

Quote:

---

To do this the "C++" way

---

mousey,
FYI - Many books and instructors teach the "C way" first. (aka C-style strings, null-terminated strings, or character arrays.) So, you can hold-off on using <string> if that's the way your class/book is structured.

[EDIT] The Windows API uses C-style strings too. Don't 'ya just love it when they teach you the hard way first! :)

Quote:

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Originally posted by DougDbug
If you're a "newbie", this may not mean much yet, but pointers are also used to pass structures and objects into functions.

---

Lol, I guess you could say I'm a newbie C++ programmer, but I'm experienced in Pascal and Basic (to an extent), and I've programmed in C before, so I know the basics :).

Quote:

---

Arrays are stored sequentially, so if your function can get-to the first character, it can get to 'em all. If fact, passing a pointer is the most common way of doing this sort of thing. (And the most common way of getting a function to update multiple variables.)

---

So I could actually iterate through the string after passing it? I didn't actually think of this, as soon as reading the pointer only revealed the first character, I gave up :rolleyes:.

Thanks for the info.

If you use foo(*c, *d) as you mentioned and then take the address of your parameters in foo(), you will get the c-string as you would expect.

Code:

---

#include <iostream>

void foo(char& c)
{
  std::cout << &c << std::endl;
}

int main()
{
  char* c = "hello world";
  foo(*c);
}

---

Thanks, that's really useful :)

use * or [] when refering to C style strings. I can't think of an appropriate use for & when it comes to C style strings----though I suspect somebody may prove me wrong very shortly.