Conditional control structures in PHP

Conditional control structure in PHP

In PHP programming, conditional control structure is a very important syntax, which allows the program to execute according to different conditions different code blocks. By using conditional control structures, we can implement the branching logic of the program and determine the execution path of the program based on the result of the condition. This article will introduce the commonly used conditional control structures in PHP, including if statements, else statements, elseif statements and switch statements, and give specific code examples.

The if statement is the most basic conditional control structure in PHP, used to execute code blocks based on conditions. The basic syntax is as follows:

if (条件) {
    // 如果条件为真，执行这里的代码
}

Specific example:

$score = 80;
if ($score >= 60) {
    echo "成绩及格";
}

In the above example, if $score is greater than or equal to 60, "passing grade" will be output.

In addition to the if statement, we can also use the else statement to execute the specified code block when the condition is not true. The syntax is as follows:

if (条件) {
    // 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
}

Specific example:

$score = 50;
if ($score >= 60) {
    echo "成绩及格";
} else {
    echo "成绩不及格";
}

In the above example, if $score is less than 60, "Failed Grade" will be output.

When we need to select and execute different code blocks under multiple conditions, we can use the elseif statement. The syntax is as follows:

if (条件1) {
    // 如果条件1为真，执行这里的代码
} elseif (条件2) {
    // 如果条件2为真，执行这里的代码
} else {
    // 如果以上条件都不成立，执行这里的代码
}

Specific example:

$score = 70;
if ($score >= 90) {
    echo "优秀";
} elseif ($score >= 80) {
    echo "良好";
} elseif ($score >= 60) {
    echo "及格";
} else {
    echo "不及格";
}

In the above example, different levels are output based on the different scores of $score.

In addition to the if statement series, PHP also provides switch statements to handle multiple conditions. The switch statement is suitable for making selections among a series of fixed values. The syntax is as follows:

switch (表达式) {
    case 值1:
        // 如果表达式等于值1，执行这里的代码
        break;
    case 值2:
        // 如果表达式等于值2，执行这里的代码
        break;
    default:
        // 如果以上所有情况都不符合，执行这里的代码
}

Specific example:

$fruit = 'apple';
switch ($fruit) {
    case 'apple':
        echo "苹果";
        break;
    case 'banana':
        echo "香蕉";
        break;
    default:
        echo "其他水果";
}

In the above example, different fruit names are output based on the value of $fruit.

In short, the conditional control structure plays an important role in PHP programming. By rationally using if, else, elseif and switch statements, we can control the execution flow of the program according to different conditions and achieve flexible logic. branch. I hope that through the introduction of this article, readers can better understand the usage of conditional control structures in PHP and be able to flexibly apply them to actual programming.

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