C++ break Keyword

The break keyword in C++ is used to immediately terminate the execution of the innermost for, while, do-while loop, or a switch statement. When the break statement is encountered, the control exits the current loop or switch block and proceeds to the next statement after it.

The break statement is particularly useful for exiting loops prematurely based on certain conditions, avoiding unnecessary iterations.

Syntax

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break;
break
The keyword used to terminate the execution of the nearest enclosing loop or switch statement.

Examples

Example 1: Using break in a Loop

This example demonstrates how to use the break statement to terminate a loop when a specific condition is met.

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#include <iostream>
using namespace std;

int main() {
    for (int i = 1; i <= 10; ++i) {
        if (i == 5) {
            break; // Exit the loop when i equals 5
        }
        cout << i << " ";
    }
    cout << "Loop terminated." << endl;
    return 0;
}

Output:

1 2 3 4 Loop terminated.

Explanation:

  1. The for loop iterates from 1 to 10.
  2. When i == 5, the break statement is executed, immediately terminating the loop.
  3. The program prints numbers from 1 to 4 and exits the loop, displaying “Loop terminated.”

Example 2: Using break in a switch Statement

This example demonstrates how to use the break statement to exit a switch case block.

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#include <iostream>
using namespace std;

int main() {
    int choice = 2;

    switch (choice) {
        case 1:
            cout << "You selected option 1." << endl;
            break; // Exit the switch block
        case 2:
            cout << "You selected option 2." << endl;
            break; // Exit the switch block
        case 3:
            cout << "You selected option 3." << endl;
            break; // Exit the switch block
        default:
            cout << "Invalid choice." << endl;
    }

    return 0;
}

Output:

You selected option 2.

Explanation:

  1. The variable choice is set to 2.
  2. The switch statement evaluates the value of choice.
  3. Case 2 is executed, printing “You selected option 2.”
  4. The break statement exits the switch block, preventing the execution of subsequent cases.

Example 3: Using break in a Nested Loop

This example shows how the break statement behaves in a nested loop structure.

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#include <iostream>
using namespace std;

int main() {
    for (int i = 1; i <= 3; ++i) {
        for (int j = 1; j <= 3; ++j) {
            if (j == 2) {
                break; // Exit the inner loop
            }
            cout << "i: " << i << ", j: " << j << endl;
        }
    }

    return 0;
}

Output:

i: 1, j: 1
i: 2, j: 1
i: 3, j: 1

Explanation:

  1. The outer loop iterates over i from 1 to 3, and the inner loop iterates over j from 1 to 3.
  2. When j == 2, the break statement is executed, terminating the inner loop.
  3. The outer loop continues to the next iteration, starting the inner loop again.

Key Points about break Keyword

  1. The break keyword is used to terminate the execution of the nearest enclosing loop or switch statement.
  2. It helps prevent unnecessary iterations or case executions.
  3. In nested loops, break only exits the innermost loop where it is used.