Entry Controlled Loops in Programming

Last Updated : 30 Jun, 2026

Entry controlled loops are loops in which the condition is checked before the loop body is executed. The loop runs only if the condition evaluates to true; otherwise, it terminates without executing the loop body.

  • Condition Check: The loop condition is checked before executing the loop body.
  • Execution: If the condition is true, the loop body is executed; otherwise, the loop terminates without executing the loop body.
  • Initialization and Increment/Decrement: A for loop handles initialization, condition checking, and increment/decrement within its syntax, whereas a while loop requires initialization and increment/decrement to be managed separately.
C 
#include <stdio.h>

int main() {
    int i = 1;

    while (i <= 3) {
        printf("%d ", i);
        i++;
    }

    return 0;
}

Output
1 2 3

Types of Entry Controlled Loops

There are two types of Entry Controlled Loops in Programming:

  • For loop: It is a control flow statement in programming that allows you to execute a block of code repeatedly based on a specified condition.
  • While loop: It repeatedly executes a block of code as long as a specified condition is true and is typically used when the number of iterations is unknown.

Entry Controlled Loop in C

Below is the implementation of Entry Controlled Loop in C:

C 
#include <stdio.h>

int main()
{
    int i = 0;

    printf("Entry controlled loop using while loop:\n");
    while (i < 5) {
        printf("%d ", i);
        i++;
    }
    printf("\n");

    i = 0;

    printf("Entry controlled loop using for loop:\n");
    for (i = 0; i < 5; i++) {
        printf("%d ", i);
    }
    printf("\n");

    return 0;
}

Output
Entry controlled loop using while loop:
0 1 2 3 4 
Entry controlled loop using for loop:
0 1 2 3 4

Entry Controlled Loop in C++

Below is the implementation of Entry Controlled Loop in C++:

C++ 
#include <iostream>

using namespace std;

int main()
{
    int i = 0;

    cout << "Entry controlled loop using while loop:"
         << endl;
    while (i < 5) {
        cout << i << " ";
        i++;
    }
    cout << endl;

    i = 0;

    cout << "Entry controlled loop using for loop:" << endl;
    for (i = 0; i < 5; i++) {
        cout << i << " ";
    }
    cout << endl;

    return 0;
}

Output
Entry controlled loop using while loop:
0 1 2 3 4 
Entry controlled loop using for loop:
0 1 2 3 4

Entry Controlled Loop in Java

Below is the implementation of Entry Controlled Loop in Java:

Java 
/*package whatever //do not write package name here */

import java.io.*;

class GFG {
    public static void main(String[] args)
    {
        int i = 0;

        System.out.println("Entry controlled loop using while loop:");
        while (i < 5) {
            System.out.print(i + " ");
            i++;
        }
        System.out.println();

        i = 0;

        System.out.println("Entry controlled loop using for loop:");
        for (i = 0; i < 5; i++) {
            System.out.print(i + " ");
        }
        System.out.println();
    }
}

Output
Entry controlled loop using while loop:
0 1 2 3 4 
Entry controlled loop using for loop:
0 1 2 3 4

Entry Controlled Loop in Python

Below is the implementation of Entry Controlled Loop in Python:

Python 
# Entry controlled loop using while loop
print("Entry controlled loop using while loop:")
i = 0
while i < 5:
    print(i, end=" ")
    i += 1
print()

i = 0

print("Entry controlled loop using for loop:")
for i in range(5):
    print(i, end=" ")
print()

Output
Entry controlled loop using while loop:
0 1 2 3 4 
Entry controlled loop using for loop:
0 1 2 3 4

Entry Controlled Loop in JavaScript

Below is the implementation of Entry Controlled Loop in Javascript:

JavaScript 
// Entry controlled loop using while loop
console.log("Entry controlled loop using while loop:");
let i = 0;
while (i < 5) {
    console.log(i);
    i++;
}
console.log();

i = 0;

console.log("Entry controlled loop using for loop:");
for (let i = 0; i < 5; i++) {
    console.log(i);
}
console.log();

Output
Entry controlled loop using while loop:
0
1
2
3
4

Entry controlled loop using for loop:
0
1
2
3
4

Entry Controlled Loop in C#

Below is the implementation of Entry Controlled Loop in C#:

C# 
using System;

class GFG {
    static void Main(string[] args)
    {
        Console.WriteLine("Entry controlled loop using while loop:");
        int i = 0;
        while (i < 5) {
            Console.Write(i + " ");
            i++;
        }
        Console.WriteLine();

        i = 0;

        Console.WriteLine("Entry controlled loop using for loop:");
        for (i = 0; i < 5; i++) {
            Console.Write(i + " ");
        }
        Console.WriteLine();
    }
}

Output
Entry controlled loop using while loop:
0 1 2 3 4 
Entry controlled loop using for loop:
0 1 2 3 4

Comparison with Exit-Controlled Loops

  • In contrast, exit-controlled loops (like the do-while loop) evaluate the condition after the loop body executes, ensuring the loop body runs at least once regardless of the condition.
  • Understanding entry-controlled loops is essential for writing effective and efficient code, as they provide a structured way to repeat operations while maintaining control over the conditions for repetition.
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