C++ Do while loop
In this article, we will discuss the C++ Do-While loop with its syntax, working, key features, algorithm, and examples.
Do-While Loop:
The do-while loop constitutes a specific style of looping construct in C++ with an assured execution of the loop body at least a single time, irrespective of any condition. This occurs because the body of the loop executes prior to the verification of the condition.
Syntax:
It has the following syntax:
do {
// Loop body: Code to be executed
} while (condition);
Working:
- The loop runs the code inside the do block first.
- Once the while statement has been run, its condition is examined.
- If the condition evaluates to true, the loop is repeated.
- If the condition is false, the loop ends.
Key Features:
Several key features of the do-while loop in C++ are as follows:
1. Execution confirmed at Least Once:
Because the loop’s execution comes before the condition is verified, the do-while loop guarantees that the loop body gets run at least once, even if the condition is initially false.
2. Post-Test Loop Organization:
In contrast to the while and for loops, which verify the condition prior to the loop body being executed, the do-while loop verifies the condition after it has been executed. For activities like menu-driven programs and user input validation, this makes it helpful.
3. Adaptable and Easy to Use:
The do-while loop works well in situations like games, menus, and authentication systems where the user must interact with the application before criteria are checked. Improved control over loops in terms of execution can also be done with break and continue statements.
Algorithm:
The algorithm describes the step-by-step execution of a do-while loop:
-
Start
-
Execute the loop body (statements inside the do block).
-
Check the condition in the while statement.
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If true, go back to Step 2 and repeat the loop.
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If false, exit the loop.
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End
Pseudo Code:
BEGIN Initialize loop variable (e.g., i ← 1) DO Execute statements inside the loop Update loop variable (e.g., i ← i + 1) WHILE (condition is TRUE) END
Example 1:
Let us take an example to illustrate the do-while loop in C++.
#include <iostream>
using namespace std;
int main() {
int i = 1;
do {
cout << "Iteration: " << i << endl;
i++;
} while (i <= 5); // Condition to continue looping
return 0;
}
Output:
Iteration: 1 Iteration: 2 Iteration: 3 Iteration: 4 Iteration: 5
Explanation:
This function executes the loop body at least once even if the condition is false. This is helpful when the loop must run at least once before confirming the condition. The while condition is assessed after the loop body has been run.
Pseudo code for above code:
BEGIN SET i ← 1 DO PRINT "Iteration: ", i INCREMENT i by 1 WHILE (i ≤ 5) END
Explanation:
- The loop does not check the condition before beginning to execute.
- It first prints i’s value before increasing it.
- At the conclusion, the condition is verified; if i ≤ 5, the loop is repeated.
- The loop ends when i equals six.
Example 2:
This example illustrates how to utilize a do-while loop in a number-guessing game. The user must guess a randomly selected number between 1 and 10.
#include <iostream>
#include <cstdlib> // For rand() and srand()
#include <ctime> // For time()
using namespace std;
int main() {
int secretNumber, userGuess;
// Seed random number generator
srand(time(0));
secretNumber = rand() % 10 + 1; // Generate a number between 1 and 10
cout << "Guess a number between 1 and 10!" << endl;
do {
cout << "Enter your guess: ";
cin >> userGuess;
if (userGuess < secretNumber)
cout << "Too low! Try again." << endl;
else if (userGuess > secretNumber)
cout << "Too high! Try again." << endl;
} while (userGuess != secretNumber); // Loop until the guess is correct
cout << "Congratulations! You guessed the correct number." << endl;
return 0;
}
Output:
Guess a number between 1 and 10! Enter your guess: 5 Too high! Try again. Enter your guess: 3 Too low! Try again. Enter your guess: 4 Congratulations! You guessed the correct number.
Explanation:
- It generates a random number between 1 and 10.
- A guess is entered by the user.
- If the guess is too low, the computer compares it and provides a higher guess.
- If it is too high, a lower guess is prompted.
- The cycle is continued until the user guesses the correct number.
- If the user guesses correctly, the application displays a success message and breaks the loop.
Conclusion:
In conclusion, the do-while loop is a useful looping construct in C++. It validates the condition after executing the loop body at least once. Therefore, it is particularly effective in scenarios where user input validation, a menu-driven system, or repeat processes must finish at least once before evaluation. The do-while loop will allow the execution of code even if the condition is initially false unlike the while and for loops. Such versatility makes this construct quite applicable to number guessing games, menus that have to be navigated, and input validation checks. When the previously mentioned method is used correctly, it can be written to create interesting applications.
Frequently Asked Questions’s:
1. What distinguishes a do-while loop from a while loop?
Whereas a while loop examines the condition first and might not run at all, a do-while loop runs at least once before checking the condition.
2. Under what circumstances is a do-while loop better than a while or for loop?
When the body of the loop needs to run at least once, like in menu-driven applications or user input validation, a do-while loop is better.
3. Can a do-while loop go infinitely?
Yes, the do-while loop runs endlessly if the loop condition never turns false. If not managed correctly, this could result in an infinite loop.
4. Does a semicolon (;) need to come after the while statement?
In actuality, in order to indicate the end point of the loop statement in a do-while loop, a semicolon (;) must come after the while(condition);.
5. Can you utilize break and continue statements with a do-while loop?
While break immediately ends the loop, continue bypasses the remainder of the current iteration’s code and checks the condition for the subsequent one.