What are the php selection structure statements?

php selection structure statements include: 1. if statement, which is one of the most commonly used selection structure statements. It executes the corresponding code block based on the true or false condition; 2. switch statement, based on the value of an expression value to select and execute the corresponding code block, which can replace the nested judgment of multiple if statements; 3. The ternary operator is a concise selection structure statement that returns one of two values ​​​​according to the true or false condition. , used for simple conditional judgment, which can make the code more concise.

The operating system for this tutorial: Windows 10 system, PHP8.1.3 version, Dell G3 computer.

PHP is a widely used server-side scripting language that provides a variety of selection structure statements to help developers execute different code blocks based on different conditions. This article will introduce the commonly used selection structure statements in PHP, including if statements, switch statements and ternary operators.

1. if statement

The if statement is one of the most commonly used selection structure statements. It executes the corresponding code block based on the true or false condition. The syntax is as follows:

if (condition) {
    // 如果条件为真，执行这里的代码
} else {
    // 如果条件为假，执行这里的代码
}

if statements can be nested as needed to form multiple conditional judgments. For example:

if (condition1) {
    // 如果条件1为真，执行这里的代码
} elseif (condition2) {
    // 如果条件1为假且条件2为真，执行这里的代码
} else {
    // 如果条件1和条件2都为假，执行这里的代码
}

2. switch statement

The switch statement selects and executes the corresponding code block based on the value of an expression. It can replace the nested judgment of multiple if statements. The syntax is as follows:

switch (expression) {
    case value1:
        // 如果expression的值等于value1，执行这里的代码
        break;
    case value2:
        // 如果expression的值等于value2，执行这里的代码
        break;
    default:
        // 如果expression的值不等于任何一个case，执行这里的代码
        break;
}

Each case in the switch statement is a possible value. When the value of the expression is equal to the value of a certain case, the corresponding code block is executed. If there is no matching case, the default code block will be executed.

3. Ternary operator

The ternary operator is a concise selection structure statement that returns one of two values ​​​​depending on the true or false condition. The syntax is as follows:

(condition) ? value1 : value2;

If the condition is true, return value1; if the condition is false, return value2. For example:

$score = 80;
$result = ($score >= 60) ? "及格" : "不及格";
echo $result; // 输出"及格"

The ternary operator is suitable for simple conditional judgments and can make the code more concise.

Summary:

PHP provides a variety of selection structure statements such as if statements, switch statements, and ternary operators to meet different conditional judgment needs. Developers can choose appropriate statements to write code according to specific situations to improve the readability and execution efficiency of the program.

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