Pass a variable memory address to a function and assign a value from within.

[shaamil]

How to Pass a memory address(of a string variable) to function B and assign a value(a string) from within the function B.

Here's part of the program:

#include <stdio.h>
char sales[20];
int d;
main()
{
FunctionA(&sales);
printf("%s",sales);
}


FunctionB(int a, int *b)
{
char c[]="Hello World";
a=d;

*b=c; /* This is where I am confused */
rerturn NULL;
}

I would appreciate any help.
Thanks in advance.

Cheers.

[horace1]

you cannot return the contents of c[] by setting pointer *b to it

FunctionB(int a, int *b)
{
char c[]="Hello World";
a=d;
 
*b=c; /* This is where I am confused */
rerturn NULL;
}
 

c[] is a local variable and the contents will be lost when the function exits and b will end up pointing at grabage

you need to copy c[] to b[], e.g.

#include <iostream>
using namespace std;
 
// pass pointer to char[] to receive data
void FunctionB(char *b)
{
char c[]="Hello World";
strcpy(b, c);    // copy contents of c[] to b[]
}
 
int main()
{
    char x[20];  // must have sufficent room to receive characters
    FunctionB(x);
    cout << x << endl;
    cin.get();
}
 

(1) in the calling function you need an array of sufficent size to receive the characters
(2) you pass a pointer to this array to the function
(3) use strcpy() to copy the contents of the local array to the array in the calling function