C++ Loops

Imagine you want to print a message 10 times. Writing the same cout statement 10 times would make your program unnecessarily long. This is where loops are useful.

Loops in C++ allow you to repeat a block of code as long as a particular condition is true. They are commonly used when you need to perform the same task multiple times.

C++ provides three main types of loops: while, do-while, and for. You can also use nested loops when one loop needs to run inside another. Along with loops, break, continue, and goto can change the normal flow of execution.

while Loop in C++

The while loop is useful when you want to repeat something but don’t know exactly how many times it should run. The condition is checked before each repetition.

Syntax

while (condition)
{
    // code
}

Example

int i = 1;

while (i <= 5)
{
    cout << i << endl;
    i++;
}

Output

1
2
3
4
5

Here, the loop starts with i = 1. C++ checks whether i is less than or equal to 5. If the condition is true, the code runs and i increases by 1.

The loop stops when the condition becomes false.

do while Loop in C++

The do-while loop is similar to the while loop, but there is one important difference. The code inside the loop runs at least once, even when the condition is false.

Syntax

do
{
    // code
}
while (condition);

Example

int i = 1;

do
{
    cout << i << endl;
    i++;
}
while (i <= 5);

Output

1
2
3
4
5

Notice that the condition is written after the code. This means C++ executes the code first and checks the condition afterward.

For example:

int i = 10;

do
{
    cout << i;
}
while (i < 5);

Even though i < 5 is false, 10 will still be printed once.

for Loop in C++

The for loop in C++ is commonly used when you already know how many times you want to repeat something.

Syntax

for (initialization; condition; update)
{
    // code
}

Example

for (int i = 1; i <= 5; i++)
{
    cout << i << endl;
}

Output

1
2
3
4
5

Here:

• int i = 1 sets the starting value.
• i <= 5 decides whether the loop should continue.
• i++ increases the value after every repetition.

The for loop keeps these three parts together, which makes it convenient for counting tasks.

Nested Loops in C++

Sometimes you need one loop to run inside another loop. This is called Nested Loops in C++.

For example, suppose you want to print a small pattern:

for (int i = 1; i <= 3; i++)
{
    for (int j = 1; j <= 3; j++)
    {
        cout << "* ";
    }

    cout << endl;
}

Output

* * *
* * *
* * *

The outer loop controls the rows, while the inner loop controls the columns.

Nested loops are commonly used for patterns, tables, matrices, and other problems where one repetition depends on another.

break Statement

The break statement is used when you want to stop a loop immediately.

Example

for (int i = 1; i <= 10; i++)
{
    if (i == 5)
        break;

    cout << i << endl;
}

Output

1
2
3
4

When i becomes 5, break stops the loop completely.

continue Statement

The continue statement skips the current repetition and moves to the next one.

Example

for (int i = 1; i <= 5; i++)
{
    if (i == 3)
        continue;

    cout << i << endl;
}

Output

1
2
4
5

Here, when i becomes 3, continue skips that repetition. The loop then continues with 4.

goto Statement

The goto statement moves program execution to a labelled statement.

Example

int i = 1;

start:

cout << i << endl;
i++;

if (i <= 3)
    goto start;

Output

1
2
3

Although goto can be used to repeat code, it is generally avoided in modern C++ because it can make programs difficult to follow. for, while, and do-while loops are usually better choices.

Frequently Asked Questions (FAQs)

Written by Shubhranshu Shekhar, who has trained 20000+ students in coding.

Nidhi Srivastav