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# XV. Character Type Functions

# 介紹

The functions provided by this extension check whether a character or string falls into a certain character class according to the current locale (see also setlocale()).

When called with an integer argument these functions behave exactly like their C counterparts from `ctype.h`. It means that if you pass an integer smaller than 256 it will use the ASCII value of it to see if it fits in the specified range (digits are in 0x30-0x39). If the number is between -128 (inclusive) and 0 then 256 will be added and the check will be done on that.

When called with a string argument they will check every character in the string and will only return `TRUE` if every character in the string matches the requested criteria. When called with an empty string the result will always be `TRUE`.

Passing anything else but a string or integer will return `FALSE` immediately.

It should be noted that ctype functions are always preferred over regular expressions, and even to some equivalent str_* and is_* functions. This is because of the fact that ctype uses a native C library and thus processes significantly faster.

# 需求

None besides functions from the standard C library which are always available.

# 安裝

Beginning with PHP 4.2.0 these functions are enabled by default. For older versions you have to configure and compile PHP with --enable-ctype. You can disable ctype support with --disable-ctype.

Windows 版本的 PHP 已內建此延伸的支援﹐所以你毋須再載入附加的延伸來使用這些功能。

> 注: Builtin support for ctype is available with PHP 4.3.0.

# 執行時期組態

`php.ini`中沒有定義此延伸的組態指令。

# 資源類型

這個延伸沒有定義任何資源。

# 預先定義常數

這個延伸沒有定義任何常數。

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