for loop in C++

C++ for Loop: Syntax and Example 

The for loop in C++ is used to repeat a block of code a fixed number of times. It is especially useful when the number of iterations is known in advance. 

Syntax 

for (initialization; condition; increment/decrement)

{

    // statements to be executed repeatedly

}

Key points 

• Initialization: Declares and initializes the loop control variable (runs once). 
• Condition: Checked before each iteration. If true, the loop continues. 
• Increment/Decrement: Updates the loop variable after each iteration. 
• All three parts of the for loop are optional, but the semicolons (;) are required.

Program 1: C++ program to print 1 to 10 numbers using for loop.

#include<iostream>

using namespace std;

int main()

{

  int i;

  for(i=1; i<=10; i++)

  {

    cout << i << " ";

  }

  return 0;

}

// Output of the program

1 2 3 4 5 6 7 8 9 10

Program 2: Print even numbers from 1 to 20

#include <iostream>

using namespace std;

int main() {

    for(int i=2; i<=20; i=i+2) {

        cout << i << " ";

    }

    return 0;

}

// Output of the program

2 4 6 8 10 12 14 16 18 20

Program 3: Find sum of first N natural numbers

#include <iostream>

using namespace std;

int main() {

    int n, sum = 0;

    cout << "Enter a number: ";

    cin >> n;

    for(int i = 1; i <= n; i++) {

        sum += i;

    }

    cout << "Sum = " << sum;

    return 0;

}

/* Output

Enter a number: 5

Sum = 15

*/

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