Pointer Basics

This lesson covers the basics of pointers, one of C++'s defining features. It's for anyone searching "C++ pointer basics."

A pointer is a variable that holds "where in memory another variable is stored" (its address). Declare one with type* variableName, get an address with &variableName, and access the value it points to with *pointer.

The example gets the address of int num = 10; with int* ptr = #, and displays its contents with *ptr.

A common early mistake is confusing & (getting an address) with * (getting the value it points to). It helps to picture a pointer as "a note holding a variable's address" — that makes the difference between the address and the actual value easier to grasp.

In real projects, pointers let you pass large data to a function without copying it, making memory usage far more efficient. This tends to be the first real hurdle in learning C++, but it's a genuinely important concept.

📖 Reference code

#include <iostream>

int main() {
    int num = 10;
    int* ptr = &num;
    std::cout << "Value: " << *ptr << std::endl;
    std::cout << "Before change via address: " << num << std::endl;
    *ptr = 20;
    std::cout << "After change via address: " << num << std::endl;
    return 0;
}

✍️ Your code

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🧪 This site can't compile or run C++ directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).