What php selectors are there?

php selectors include: 1. if statement; 2. switch statement; 3. foreach loop; 4. while loop; 5. do-while loop; 6. foreach and foreach...as; 7. foreach...as...with; 8. foreach...with. Detailed introduction: 1. if statement, which is the most basic selector, used to execute different code blocks based on conditional judgment; 2. switch statement, used based on different conditions, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

PHP selector is a method used to select and filter data based on different conditions in PHP. The following are some common PHP selectors:

1. if statement: This is the most basic selector, used to execute different code blocks based on conditional judgment.

if ($condition) {  
    // 执行代码块  
}

2. Switch statement: The switch statement is used to execute different code blocks according to different conditions.

switch ($variable) {  
    case value1:  
        // 执行代码块1  
        break;  
    case value2:  
        // 执行代码块2  
        break;  
    default:  
        // 默认执行代码块  
}

3. foreach loop: The foreach loop is used to traverse an array or iterable object and execute the corresponding code block based on the value of each element.

foreach ($array as $value) {  
    // 执行代码块  
}

4. While loop: The while loop is used to repeatedly execute a block of code when certain conditions are met.

while ($condition) {  
    // 执行代码块  
}

5. do-while loop: The do-while loop is similar to the while loop, but it will first execute the code block once and then check whether the condition is met. If satisfied, execution of the code block continues until the condition is not satisfied.

do {  
    // 执行代码块  
} while ($condition);

6. foreach and foreach...as: Both methods can be used to traverse arrays, but they are different in the way they handle array elements. foreach...as allows you to directly access the value of an array element without using an index.

foreach ($array as $key => $value) {  
    // 执行代码块，使用$key和$value访问数组元素的值和键名  
}

7. foreach...as...with: This selector can access the key name, value and associated array of array elements at the same time. It allows you to access the values ​​of an associative array while iterating over the array.

foreach ($array as $key => $value) with ($assocArray) {  
    // 执行代码块，使用$key、$value和关联数组访问数组元素的值、键名和关联数组的值  
}

8. foreach...with: This selector allows you to access the values ​​of an associative array when traversing the array. It doesn't require key names, just the values ​​from the associative array.

foreach ($assocArray as $value) {  
    // 执行代码块，使用$value访问关联数组的值  
}

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