How to convert PHP string to integer

How to convert PHP to integer: 1. Add the target type enclosed in parentheses before the variable to be converted; 2. Use PHP's built-in function intval to convert the variable; 3. Use sprintf "%d" formats the specified variable to complete the conversion.

PHP Convert string to integer

In PHP, we can use 3 ways to convert string is an integer.

1. Forced type conversion method

Forced type conversion method is the method of "adding the target type enclosed in parentheses before the variable to be converted".

<?php 
$foo = "1"; // $foo 是字符串类型 
$bar = (int)$foo; // $bar 是整型 
?>

For integers, the cast type name is int or integer.

2. Built-in function method

The built-in function method uses PHP's built-in function intval to convert variables.

<?php 
$foo = "1"; // $foo 是字符串类型 
$bar = intval($foo); // $bar 是整型 
?>

The format of the intval function is: int intval(mixed $var [, int $base]);

3. Format string method

Format string The method is to use sprintf's %d to format the specified variable to achieve type conversion.

<?php 
$foo = "1"; // $foo 是字符串类型 
$bar = sprintf("%d", $foo); // $bar 是字符串类型 
?>

Strictly speaking, the conversion result of sprintf is still string type, so it should not be regarded as a way to convert strings into integers. But the string value after his processing has indeed become "an integer that is forced to be converted to a string type."

Performance

int > intval > sprintf

From the perspective of readability, the sprintf method code is relatively long, and the result may need to be forced type conversion again, while the intval function is a typical procedure-oriented method Conversion and forced type conversion more directly convey the idea of ​​"I want to convert" to the reader.

In terms of efficiency, forced type conversion is also the fastest conversion method (the integer variable value can be obtained directly).

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