continue的用法 The continue statement in loops

Introduction

Continue is a widely used keyword in programming languages, particularly in loops and conditional statements. It allows the program to skip a specific iteration or move to the next iteration of the loop without executing the remaining statements in the current iteration. In this article, we will explore the various use cases of the continue keyword in programming.

The continue statement in loops

The continue statement is commonly used in loops to skip a specific iteration and move to the next iteration without executing the statements after the continue keyword. This is useful when the program needs to perform a specific action for a certain condition and skip the rest of the loop for that iteration. The continue statement is often used in conjunction with conditional statements to achieve this behavior.

Let's consider an example:

for i in range(1, 11):
    if i % 2 == 0:
        continue
    print(i)

In this code snippet, we use a for loop to iterate over the numbers from 1 to 10. If the current number is even, the continue statement skips the remaining statements in the loop and moves to the next iteration. Otherwise, the program executes the print statement and moves to the next iteration.

The output of this code will be:

1
3
5
7
9

The continue statement in nested loops

The continue statement can also be used in nested loops to skip to the next iteration of the inner loop, without affecting the outer loop. This is useful when the program needs to skip a certain condition in the inner loop and continue iterating over the remaining items. Let's consider an example:

for i in range(1, 4):
    for j in range(1, 4):
        if j == 2:
            continue
        print(i, j)

In this code snippet, we use two nested for loops. When the inner loop encounters j = 2, the continue statement skips the remaining statements in the inner loop and moves to the next iteration. However, the outer loop continues to iterate over the remaining items.

The output of this code will be:

1 1
1 3
2 1
2 3
3 1
3 3

The continue statement in while loops

The continue statement can also be used in while loops to skip a specific iteration and move to the next iteration without executing the remaining statements in the current iteration. This is useful when the program needs to perform a specific action for a certain condition and skip the rest of the loop for that iteration. Let's consider an example:

i = 0
while i < 5:
    i += 1
    if i == 3:
        continue
    print(i)

In this code snippet, we use a while loop to iterate over the numbers from 1 to 5. If the current number is 3, the continue statement skips the remaining statements in the loop and moves to the next iteration. Otherwise, the program executes the print statement and moves to the next iteration.

The output of this code will be:

1
2
4
5

The continue statement in switch statements

In some programming languages, such as C and Java, the continue statement can also be used in switch statements to skip a specific case and move to the next case without executing the remaining statements in the current case. This is useful when the program needs to handle a specific condition and skip the rest of the cases for that condition. Let's consider an example:

switch (i) {
    case 1:
        doSomething();
        break;
    case 2:
        break;
    case 3:
        doSomethingElse();
        continue;
    default:
        doDefault();
        break;
}

In this code snippet, we use a switch statement to handle different cases based on the value of i. If the current case is 3, the continue statement skips the remaining statements in the case and moves to the next case. Otherwise, the program executes the statements for the current case and moves to the next case.

Conclusion

The continue statement is a powerful tool in programming, allowing programmers to skip specific iterations in loops and move on to the next iteration without executing the remaining statements in the current iteration. It is commonly used in conjunction with conditional statements and can also be used in nested loops and switch statements. By leveraging the continue keyword, programmers can optimize their code and achieve more efficient and streamlined execution.