Learn Do-While Loop

What is the Difference Between while and do-while?

The do-while loop is another type of loop in Java that is similar to the while loop. However, it has one important difference: the condition is checked at the end of each iteration. This means the code block will always execute at least once before evaluating the condition.

Here's the basic syntax of the do-while loop:

Main.java


              123
            
do {
    // Code block
} while (condition);

Here are some key points about the do-while loop:

Execution flow: the code block runs first, then the condition is checked; if true, the loop continues, otherwise it ends;
Guaranteed execution: the loop always runs at least once because the condition is checked after execution;
Variable scope: variables declared inside the loop are accessible only within it;
Use cases: useful when you need to execute code at least once, such as prompting user input or iterating through a list.

Let's look at a simple example of usage and compare the results of a while loop and a do-while loop on a very basic example:

main.java


              123456789
            
package com.example;

public class Main {
    public static void main(String[] args) {
        do {
            System.out.println("Do-while loop executed successfully");
        } while (1 < 0);
    }
}

while loop:

main.java


              123456789
            
package com.example;

public class Main {
    public static void main(String[] args) {
        while (1 < 0) {
            System.out.println("While loop executed successfully");
        }
    }
}

We can see that when executing the do-while loop with a condition that is always false, we executed the body of the loop once, while the while loop simply gave us an error.

1. What will be the output of the code?

2. What will be the output of the code?

Everything was clear?

Thanks for your feedback!

Section 3. Chapter 3

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What is the Difference Between while and do-while?

Here's the basic syntax of the do-while loop:

Main.java


              123
            
do {
    // Code block
} while (condition);

Here are some key points about the do-while loop:

Execution flow: the code block runs first, then the condition is checked; if true, the loop continues, otherwise it ends;
Guaranteed execution: the loop always runs at least once because the condition is checked after execution;
Variable scope: variables declared inside the loop are accessible only within it;
Use cases: useful when you need to execute code at least once, such as prompting user input or iterating through a list.

Let's look at a simple example of usage and compare the results of a while loop and a do-while loop on a very basic example:

main.java


              123456789
            
package com.example;

public class Main {
    public static void main(String[] args) {
        do {
            System.out.println("Do-while loop executed successfully");
        } while (1 < 0);
    }
}

while loop:

main.java


              123456789
            
package com.example;

public class Main {
    public static void main(String[] args) {
        while (1 < 0) {
            System.out.println("While loop executed successfully");
        }
    }
}

We can see that when executing the do-while loop with a condition that is always false, we executed the body of the loop once, while the while loop simply gave us an error.

1. What will be the output of the code?

2. What will be the output of the code?

Everything was clear?

Thanks for your feedback!

Section 3. Chapter 3