How to convert php string to integer

How to convert PHP string to integer: 1. Force type conversion through "(int)$foo"; 2. Conversion through "intval($foo)" function; 3. Through "sprintf( "%d", $foo);" to convert.

The operating environment of this article: windows7 system, PHP7.1 version, DELL G3 computer

Conversion method

In PHP , we can use 3 ways to convert strings into integers.

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

Built-in function method is to use PHP’s built-in function intval to perform variable conversion operations.

<?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 method is to use %d of sprintf to format the specified variable to achieve the purpose of 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, and the intval function It is a typical process-oriented conversion, and forced type conversion more directly conveys the idea of ​​"I want to convert" to the reader. [Recommended learning: PHP video tutorial]

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

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