Returning Strings in a Function

[suchanoob]

It's been a while since I've worked with C++ and am shaky at remembering how to use arrays properly. I need to return a string from a function but for some reason it's not running correctly. Here's a simplified version.

#include <iostream>
using namespace std;
char* array();
int main()
{
    cout<<array();
}
char* array()
{
    char x[80]="Hello world!";
    return x;
}

This code results in some strange characters being displayed, but everything past the letter o comes up fine. Anyone know what I did wrong?

[Dy7SLyTq]

as a side note if your using the array for strings, instead do #include <string>
which gives you access to the string data type. second do:
char x[] = "Hello, world!";
return x;

if you have [int] = "string"

and int > len of string, the remaining spots are initialized to '\0'

[suchanoob]

Okay thanks, though I find it odd that putting [int] would affect the first few characters.

[LB]

#include <iostream>

char const*array();

int main()
{
    std::cout << array();
}
char const*array()
{
    return "Hello world!";
}

[Dy7SLyTq]

@LB: i thought of that but he wants to return an array not a string literal

[LB]

If he wants to return an array he had better stop using C++

I agree that he should use std::vector

[suchanoob]

While the above helped for returning an array declared within the function, I'm having the same problem with an array assembled in the function.

#include <iostream>
using namespace std;
char* digits();
int main()
{
    cout<<digits();
    system("pause");
    return 0;
}
char* digits()
{
    char x[80];
    int cnt;
    for(cnt=0;cnt<10;cnt++)
    x[cnt]=(char)cnt+48;
    x[10]='\0';
    return x;
}

It's supposed to list digits 0 through 9 but instead outputs some odd characters and then 456789. I'm not really sure why.

[rcast]

I'm pretty sure it's outputting those odd characters and numbers because you've initialized digits() as a pointer with *, it's displaying the member location of that function. If you wanted to output digits, you would use cout<<*digits . However, I'm not sure if you can return an array, as I am very new at C++ - But if you directly cout x array via the digits function instead of trying to return the array - it works.

char digits()
{
    char x[80];
    int cnt;
    for(cnt=0;cnt<10;cnt++)
    x[cnt]=(char)cnt+48;
    x[10]='\0';
	    cout<<x<<endl;

}

int main()
{
    cout<<digits();
    system("pause");
    return 0;
}

EDIT ** Sorry - I re-read this thread and apparently you are after returning the array from the function return

[AbstractionAnon]

You're trying to return a pointer to storage that has gone out of scope.
When digits exits, the storage for x is no longer valid.

Try this instead:

#include <string>

string digits()
{  string x; 
    int cnt;
    for(cnt=0;cnt<10;cnt++)
        x += (char)cnt+48;
    return x;
}

[suchanoob]

Ah I get it, I had to initialize the array outside the function, pass it in, then return it. This logic gets really complicated. Thanks for the help.

[S6k9GNh0]

You can return an array as long as you know how that array's memory is managed. You must also know the length of that array. This is sometimes done in C libraries with a init/quit type of library.

AbstractionAnon, understand that that can be a relatively heavy operation.