Passing a pointer (memory address) to a function C++ code sample


Compiler: Visual C++ Express Edition 2005

Compiled on Platform: Windows 2003 Server Standard Edition

Header file: Standard

Additional project setting: Set project to be compiled as C++

Project -> your_project_name Properties -> Configuration Properties -> C/C++ -> Advanced -> Compiled As: Compiled as C++ Code (/TP)

Other info: none

To do: Passing pointers to a function, modify the data, return the pointer to main() in C++ programming

To show: How to pass data to a function using a pointer, modify the data and return to main() in C++ programming


// illustrates sending to a function memory address of variable and then modify the content

#include <iostream>

using namespace std;


void main(void)


int x = 4, y = 7;


// function prototype

void addcon(int*, int*);


cout<<"\nInitial value of x = "<<x;

cout<<"\nInitial value of y = "<<y;

cout<<"\nThen calls function addcon()\n";

cout<<"\nBringing along the &x = "<<&x<<endl;

cout<<"and &y = "<<&y<<"\n";


// function call, address of x any y are passed to addcon()

addcon(&x, &y);

cout<<"\nAdd 10...";

cout<<"\nNew value of x = "<<x;

cout<<"\nminus 10...";

cout<<"\nNew value of y = "<<y<<endl;



// function definition, parameters are pointers...

void addcon(int *px, int *py)


// adds 10 to the data stored in memory pointed to by px

*px = *px + 10;

// minus 10 to the data stored in memory pointed to by py

*py = *py - 10;



Output example:


Initial value of x = 4

Initial value of y = 7

Then calls function addcon()

Bringing along the &x = 0012FF60

and &y = 0012FF54

Add 10...

New value of x = 14

minus 10...

New value of y = -3

Press any key to continue . . .



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