Difference between for and while loop in C, C++, Java
Last Updated :
04 Sep, 2023
In C, C++, and Java, both for loop and while loop is used to repetitively execute a set of statements a specific number of times. However, there are differences in their declaration and control flow. Let's understand the basic differences between a for loop and a while loop.
for Loop
A for loop provides a concise way of writing the loop structure. Unlike a while loop, a for loop declaration consumes the initialization, condition, and increment/decrement in one line thereby providing a shorter, easy-to-debug structure of looping.
Syntax
for (initialization condition; testing condition; increment/decrement)
{
// statement(s)
}Flowchart of for Loop
Example: Program to Demonstrate How to Use for Loop
C
// C Program to illustrate the use of for loop
#include <stdio.h>
int main()
{
// loop variable
int i = 0;
// for loop that prints "GFG" 5 times
for (i = 5; i < 10; i++) {
printf("GFG\n");
}
return 0;
}
// CPP program to demonstrate
// for loop
#include <iostream>
using namespace std;
int main()
{
// Initialize variable 'i' with a value of 0
int i = 0;
// Iterate using a for loop from 5 to 9 (inclusive)
for (i = 5; i < 10; i++) {
// Print "GFG" on each iteration
cout << "GFG\n";
}
return 0;
}
// Java program to illustrate the use of for loop
import java.io.*;
class GFG {
public static void main(String[] args)
{
// loop variable
int i = 0;
// for loop
for (i = 5; i < 10; i++) {
System.out.println("GfG");
}
}
}
OutputGFG
GFG
GFG
GFG
GFG
Looping Infinite Times
C
// C program to demonstrate
// infinite for loop
#include <stdio.h>
int main()
{
// Infinite loop using a for loop with no condition
// specified The absence of a condition means the loop
// will continue indefinitely until it is explicitly
// interrupted or terminated.
for (;;) {
printf("GFG\n");
}
return 0;
}
// C++ program to demonstrate
// infinite for loop
#include <iostream>
using namespace std;
int main()
{
// Infinite loop using a for loop with no condition
// specified The absence of a condition means the loop
// will continue indefinitely until it is explicitly
// interrupted or terminated.
for (;;) {
// Print "GFG" on each iteration
cout << "GFG\n";
}
return 0;
}
// Java program to illustrate the use of for loop
import java.io.*;
class GFG {
public static void main(String[] args)
{
// infinite for loop
for (;;) {
System.out.println("GFG!");
}
}
}
Output
GFG
GFG
GFG
...
...
...
{truncated}while Loop
A while loop is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition. The while loop can be thought of as a repeating if statement.
Syntax
while (boolean condition)
{
// loop statements...
}Flowchart of while Loop
Example: CPP Program to Demonstrate while Loop
C
// C program to demonstrate while loop
#include <stdio.h>
int main()
{
// loop variable definition
int i = 5;
// while loop that prints "GFG" 5 times
while (i < 10) {
printf("GFG\n");
i++;
}
return 0;
}
// C++ program to demonstrate
// while loop
#include <iostream>
using namespace std;
int main()
{
// Initialize variable 'i' with a value of 5
int i = 5;
// Execute the loop as long as 'i' is less than 10
while (i < 10) {
// Increment 'i' by 1 on each iteration
i++;
// Print "GFG" on each iteration
cout << "GFG\n";
}
return 0;
}
import java.io.*;
class GFG {
public static void main(String[] args)
{
int i = 5;
while (i < 10) {
i++;
System.out.println("GfG");
}
}
}
OutputGFG
GFG
GFG
GFG
GFG
Looping Infinite Times
C
// C program to domonstrate
// infinite while loop
#include <stdio.h>
int main()
{
// Condition is always true which results in infinite
// loop
while (1)
printf("GFG\n");
return 0;
}
// C++ program to domonstrate
// infinite while loop
#include <iostream>
using namespace std;
int main()
{
// Condition is always true which results in infinite
// loop
while (1)
cout << "GFG\n";
return 0;
}
// C++ program to domonstrate
// infinite while loop
import java.io.*;
class GFG {
public static void main(String[] args)
{
// loop variable
int i = 5;
// while loop
while (i < 10) {
System.out.println("GFG\n");
}
}
}
Output
GFG
GFG
GFG
...
...
...
{truncated}Difference Between for Loop and while Loop
The major differences between for loop and while loop in C, C++ and Java are as follows:
for Loop
| while Loop
|
|---|
| Initialization may be either in the loop statement or outside the loop. | Initialization is always outside the loop. |
| Once the statement(s) is executed then increment is done. | The increment can be done before or after the execution of the statement(s). |
| It is normally used when the number of iterations is known. | It is normally used when the number of iterations is unknown. |
| Condition is a relational expression. | The condition may be an expression or non-zero value. |
| It is used when initialization and updation of conditions are simple. | It is used for complex initialization. |
| For loop is entry controlled loop. | While loop is also entry controlled loop. |
| Syntax: for ( init ; condition ; iteration ) { statement(s); } | Syntax: while ( condition ) { statement(s); } |
| The for loop is used when the number of iterations is known. | The while loop is used when the number of iterations is unknown. |