C++ For Loop - C++ Tutorial

When you know the exact number of times you want to execute a block of code, the for loop is the best choice. It provides a clear structure for initializing variables, setting conditions, and updating values—all within a single line.

How the for Loop Works

The for loop contains three main components, executed in a specific order:

Initialization (Statement 1): Runs once before the loop starts.
Condition (Statement 2): Evaluated before each iteration; the loop continues as long as this condition is true.
Update (Statement 3): Executes after each iteration to modify loop variables.

Syntax

for (statement 1; statement 2; statement 3) {
    // Code to execute in the loop
}

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​x
 
for (statement 1; statement 2; statement 3) {    // Code to execute in the loop}​

Example: Counting Gears of a Motorcycle

#include <iostream>
using namespace std;

int main() {
    for (int gear = 1; gear <= 5; gear++) {
        cout << "Gear: " << gear << "\n";
    }

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    for (int gear = 1; gear <= 5; gear++) {        cout << "Gear: " << gear << "\n";    }​    return 0;}​

Explanation of the Example

Initialization (int gear = 1): Sets gear to 1 before the loop begins.
Condition (gear <= 5): The loop continues as long as gear is less than or equal to 5.
Update (gear++): Increments gear by 1 after each iteration.

Output

Gear: 1  
Gear: 2  
Gear: 3  
Gear: 4  
Gear: 5

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Gear: 1  Gear: 2  Gear: 3  Gear: 4  Gear: 5  ​

Example: Printing Even Numbers

This example demonstrates printing even values within a specific range.

#include <iostream>
using namespace std;

int main() {
    for (int rpm = 0; rpm <= 10; rpm = rpm + 2) {
        cout << rpm << "\n";
    }

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    for (int rpm = 0; rpm <= 10; rpm = rpm + 2) {        cout << rpm << "\n";    }​    return 0;}​

How It Works

Initialization (int rpm = 0): Starts with an RPM value of 0.
Condition (rpm <= 10): The loop runs as long as rpm is 10 or less.
Update (rpm = rpm + 2): Increases rpm by 2 after each iteration.

Output

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0  2  4  6  8  10  ​