C++ Do-while loop

Do-while loops are control flow statements in C++ that repeatedly run a block of code until the desired condition is false. A do-while loop always runs the code block at least once, unlike the while loop which only does so when the condition is first true.

Basic syntax of Do-while loop:

do {
    // code to be executed
} while (condition);

Here, until the condition inside the parenthesis () is true, the code inside the curly braces is continually performed. At the conclusion of each iteration, the condition is verified; if true, the loop continues to run. If the predicate is false, the loop ends, and the statement after the loop is executed next in the program.

do-while-loop

Example of Do-while loop:

#include <iostream>
using namespace std;

int main() {
    int i = 1;
    do {
        cout << i << " ";
        i++;
    } while (i <= 10);
    
    return 0;
}

Output:

1 2 3 4 5 6 7 8 9 10

Another Example:

#include <iostream>
#include <cstdlib>
using namespace std;

int main() {
    int num;
    char choice;
    
    do {
        num = rand() % 100 + 1; // generate a random number between 1 and 100
        cout << "The random number is: " << num << endl;
        
        cout << "Do you want to generate another random number? (y/n): ";
        cin >> choice;
    } while (choice == 'y' || choice == 'Y');
    
    return 0;
}

Output:

The random number is: 42
Do you want to generate another random number? (y/n): y
The random number is: 87
Do you want to generate another random number? (y/n): y
The random number is: 3
Do you want to generate another random number? (y/n): n

Advantages of do-while loop:

  • It is advantageous to utilize the loop since it will always run at least once if you need to carry out an action before testing a condition.

  • The loop structure is simpler to read and comprehend than alternative loop forms, which reduces the likelihood of errors.

  • The loop body can be used to repeatedly ask the user for input, and the loop condition can be used to determine whether the input is legitimate.

Disadvantages of  do-while loop:

  • If the condition is not properly defined or if the loop body does not update the loop condition, it may result in infinite loops.

  • While the loop body will always execute at least once, it can be less effective than other loop structures if the loop condition is known before entering the loop.

  • When the loop condition and the loop body are complex, it could be more challenging to maintain and modify than other loop structures.

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