How is the if statement used in the C language?

2 years ago
Olivia Parker
2 minutes

The if statement in the C language is used to execute a specific code block based on a given condition. Its general syntax is as follows:

if (condition) {
    // 当条件为真时执行的代码块
}

If the condition is true (non-zero), the code block following the if statement will be executed. If the condition is false (zero), the code block will be skipped and the next code block will be executed.

The if statement can also be used with the else keyword to provide an alternative code block to execute when the condition is false. Its syntax form is as follows:

if (condition) {
    // 当条件为真时执行的代码块
} else {
    // 当条件为假时执行的代码块
}

In this scenario, if the condition is true, the if code block will be executed; if the condition is false, the else code block will be executed.

Another option is to use the “else if” keyword to add more conditional checks. Its syntax form is as follows:

if (condition1) {
    // 当条件1为真时执行的代码块
} else if (condition2) {
    // 当条件2为真时执行的代码块
} else {
    // 当所有条件都为假时执行的代码块
}

In this situation, the first condition checked is condition 1. If it is true, the if code block is executed. If it is false, then condition 2 is checked. If condition 2 is true, the else-if code block is executed. If all conditions are false, the else code block is executed.

Please note that the condition must be an expression that evaluates to a boolean value (true or false). Common comparison operators (such as ==, !=, <, >, <=, >=) can be used to construct conditions.

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