11
OctUnderstanding Do...While Loop in C++
21 May 2024
Beginner
1.52K Views
10 min read
Do...While Loop in C++: An Overview
Now, it's time to look at the third and the last loop in our C++ programming tutorial i.e. thedo...while
loop. After understanding the for loop and while loop in detail, it will be effortless for you to understand the do...while
loop in every aspect.Do...While Loop in C++
It is an exit-controlled loop. It prints the output at least once before checking the condition. Afterwards, the condition is checked and the execution of the loop begins.
Syntax
do{
//code to be executed
}while(testCondition);
- The body of the loop executes before checking the condition.
- If the
testCondition
istrue
, the loop body executes again. - Again the
testCondition
is evaluated. - The process repeats until the
testCondition
becomesfalse
.
Example to demonstrate do...while loop in C++ Compiler
#include <iostream>
using namespace std;
int main() {
int i = 0;
do {
cout << i + 1 << endl;
i++;
} while (i < 10);
return 0;
}
- The above code prints numbers from 1 to 10 using the
do...while
loop in C++. - It prints 1 before checking if
i<10
. - It checks the condition
i<10
and executes untili
becomes 10
Output
1
2
3
4
5
6
7
8
9
10
Read More - C++ Interview Interview Questions and Answers
Nested Do...While Loop in C++
It is ado...while
loop inside any do...while
loop.Example to demonstrate Nested do...while loop in C++
#include <iostream>
using namespace std;
int main() {
int i = 1;
do {
int j = 1;
do {
cout << i << " * " << j << " = " << i * j << endl;
j++;
} while (j <= 10);
i++;
} while (i <= 2);
return 0;
}
- The above code creates and outputs multiplication tables of 1 and 2 from 1 to 10 using a
nested
loop structure. - It iterates over the values of
i
(1 and 2) andj
(1 to 10), outputting the result ofi * j
after each iteration using twonested do...while
loops.
Output
1 * 1 = 1
1 * 2 = 2
1 * 3 = 3
1 * 4 = 4
1 * 5 = 5
1 * 6 = 6
1 * 7 = 7
1 * 8 = 8
1 * 9 = 9
1 * 10 = 10
2 * 1 = 2
2 * 2 = 4
2 * 3 = 6
2 * 4 = 8
2 * 5 = 10
2 * 6 = 12
2 * 7 = 14
2 * 8 = 16
2 * 9 = 18
2 * 10 = 20
Infinite do...while loop in C++
It gets created when thetestCondition
remains true
.Syntax
do
{
// body of the loop
}while(true);
Example to demonstrate infinite do...while loop in C++ Editor
#include <iostream>
using namespace std;
int main() {
do {
cout << "This is an infinite do-while loop." << endl;
} while (true);
return 0; // This return statement may never be reached.
}
Output
This is an infinite do-while loop.
This is an infinite do-while loop.
This is an infinite do-while loop.
...