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 Break and continue
  • The goto statement is a control flow statement that causes the CPU to jump to another spot in the code.
  • This spot is identified through use of a statement label.
  • The following is an example of a goto statement and statement label:
  • In C++ programming, goto statement is used for altering the normal sequence of program execution by transferring control to some other part of the program.

Syntax of goto Statement

goto label;
... .. ...
... .. ...
... .. ...
label: 
statement;
... .. ...
  • In the syntax above, label is an identifier. When goto label; is encountered, the control of program jumps to label: and executes the code below it.
 goto statement

Example: goto Statement

// This program calculates the average of numbers entered by user.
// If user enters negative number, it ignores the number and 
   calculates the average of number entered before it.

# include <iostream>
using namespace std;

int main()
{
    float num, average, sum = 0.0;
    int i, n;

    cout << "Maximum number of inputs: ";
    cin >> n;		

    for(i = 1; i <= n; ++i)
    {
        cout << "Enter n" << i << ": ";
        cin >> num;
        
        if(num < 0.0)
        {
           // Control of the program move to jump:
            goto jump;
        } 
        sum += num;
    }
    
jump:
    average = sum / (i - 1);
    cout << "\nAverage = " << average;
    return 0;
}

Output

Maximum number of inputs: 10
Enter n1: 2.3
Enter n2: 5.6
Enter n3: -5.6

Average = 3.95
  • You can write any C++ program without the use of goto statement and is generally considered a good idea not to use them.

Reason to Avoid goto Statement

  • The goto statement gives power to jump to any part of program but, makes the logic of the program complex and tangled.
  • In modern programming, goto statement is considered a harmful construct and a bad programming practice.
  • The goto statement can be replaced in most of C++ program with the use of break and continue statements.

C++ break and continue Statement

  • In C++, there are two statements break; and continue; specifically to alter the normal flow of a program.
  • Sometimes, it is desirable to skip the execution of a loop for a certain test condition or terminate it immediately without checking the condition.
  • For example: You want to loop through data of all aged people except people aged 65. Or, you want to find the first person aged 20.
  • In scenarios like these, continue; or a break; statement is used.
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C++ break Statement

  • The break; statement terminates a loop (for, while and do..while loop) and a switch statement immediately when it appears.

Syntax of break

break;
  • In real practice, break statement is almost always used inside the body of conditional statement (if...else) inside the loop.

How break statement works?

 break

C++ program to add all number entered by user until user enters 0.

// C++ Program to demonstrate working of break statement

#include <iostream>
using namespace std;
int main() {
    float number, sum = 0.0;

    // test expression is always true
    while (true)
    {
        cout << "Enter a number: ";
        cin >> number;
        
        if (number != 0.0)
        {
            sum += number;
        }
        else
        {
            // terminates the loop if number equals 0.0
            break;
        }

    }
    cout << "Sum = " << sum;

    return 0;
}

Output

Enter a number: 4
Enter a number: 3.4
Enter a number: 6.7
Enter a number: -4.5
Enter a number: 0
Sum = 9.6
  • In the above program, the test expression is always true.
  • The user is asked to enter a number which is stored in the variable number. If the user enters any number other than 0, the number is added to sum and stored to it.
  • Again, the user is asked to enter another number. When user enters 0, the test expression inside if statement is false and body of else is executed which terminates the loop.
  • Finally, the sum is displayed.

C++ continue Statement

  • It is sometimes necessary to skip a certain test condition within a loop. In such case,continue; statement is used in C++ programming.

Syntax of continue

continue;
  • In practice, continue; statement is almost always used inside a conditional statement.

Working of continue Statement

 continue

Example 2: C++ continue

C++ program to display integer from 1 to 10 except 6 and 9.

#include <iostream>
using namespace std;

int main()
{
    for (int i = 1; i <= 10; ++i)
    {
        if ( i == 6 || i == 9)
        {
            continue;
        }
        cout << i << "\t";
    }
    return 0;
}

Output

1	2	3	4	5      7	8	10	
  • In above program, when i is 6 or 9, execution of statement cout << i << "\t"; is skipped inside the loop using continue; statement.

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