How to implement intval() function in php

PHP is a scripting language widely used in Web development. It is easy to learn, powerful, and has detailed documentation. Among them, the intval() function is a very important function, used to convert a string into an integer. This article will introduce how to implement the intval() function in PHP.

First, let us understand the role of the intval() function. The intval() function is a commonly used cast conversion function in PHP, which is used to convert the value of a variable into an integer. Its syntax is as follows:

intval ( mixed $var , int $base = 10 ) : int

Among them, $var is the variable to be converted, $base represents the base number, and the default is decimal. The function returns an integer type.

Next, we will learn how to implement the intval() function by analyzing the process of function implementation.

1. Determine whether the variable to be converted is of string type.

function myIntval($var, $base = 10)
{
    if(!is_string($var)) { // 如果$var不是字符串类型，则不需要转换，直接返回
        return $var;
    }
}

2. Processes string conversion in different bases.

function myIntval($var, $base = 10)
{
    if(!is_string($var)) { // 如果$var不是字符串类型，则不需要转换，直接返回
        return $var;
    }
    $result = '';
    // 根据不同进制数处理字符串
    switch($base){
        case 2:
            preg_match('/^[01]+/', $var, $match);
            $result = base_convert($match[0], 2, 10);
            break;
        case 8:
            preg_match('/^[0-7]+/', $var, $match);
            $result = base_convert($match[0], 8, 10);
            break;
        case 16:
            preg_match('/^[\da-fA-F]+/', $var, $match);
            $result = base_convert($match[0], 16, 10);
            break;
        default:
            $result = $var;
            break;
    }
    return (int)$result; // 强制类型转换
}

The above code matches the string through the preg_match() function, processes it according to different base numbers, and finally uses forced type conversion to convert the converted string into an integer type.

3. Consider other abnormal situations

function myIntval($var, $base = 10)
{
    if(!is_string($var)) { // 如果$var不是字符串类型，则不需要转换，直接返回
        return $var;
    }
    $result = '';
    // 根据不同进制数处理字符串
    switch($base){
        case 2:
            preg_match('/^[01]+/', $var, $match);
            $result = base_convert($match[0], 2, 10);
            break;
        case 8:
            preg_match('/^[0-7]+/', $var, $match);
            $result = base_convert($match[0], 8, 10);
            break;
        case 16:
            preg_match('/^[\da-fA-F]+/', $var, $match);
            $result = base_convert($match[0], 16, 10);
            break;
        default:
            $result = $var;
            break;
    }
    if($result == '') { // 如果转换后的结果为空字符串，则表明原字符串不满足要求，返回0
        return 0;
    }
    return (int)$result; // 强制类型转换
}

The above code is based on the original addition of the judgment that the converted result is an empty string. If the original string does not satisfy the conversion Required, the function returns 0.

To sum up, we can implement a simple but complete intval() function through the above code. This is an example of writing efficient function code through logical processing after understanding the basic syntax of PHP and how to use functions.

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