PHP和MySQL的删除空白函数详解

发布时间：2022-06-15 14:49:07 所属栏目：MySql教程来源：互联网

导读：作为黄金搭档,PHP和MySQL都有自己的删除空白函数,而且函数名字也一样:trim(),ltrim(),rtrim(),当然,作为编程语言,PHP删除空白函数更为强大. 对 ltrim()和rtrim(),从其英语解释来看: 以下是引用片段: PHP为:Strip whitespace (or other characters) 对other ch

作为黄金搭档,PHP和MySQL都有自己的删除空白函数,而且函数名字也一样:trim(),ltrim(),rtrim(),当然,作为编程语言,PHP删除空白函数更为强大.

对 ltrim()和rtrim(),从其英语解释来看:

以下是引用片段:

PHP为:Strip whitespace (or other characters)

对“other characters”，手册解释为,以下是引用片段:

" " (ASCII 32 (0x20)), an ordinary space.
"t" (ASCII 9 (0x09)), a tab.
"n" (ASCII 10 (0x0A)), a new line (line feed).
"r" (ASCII 13 (0x0D)), a carriage return.
"" (ASCII 0 (0x00)), the NUL-byte.
"x0B" (ASCII 11 (0x0B)), a vertical tab.
不过,MySQL的trim()函数也增加了对其他字符的删除,具体请见下面从手册上摘抄的解释.

以下为MySQL的函数解释:

mysql> SELECT LTRIM(' barbar');
        -> 'barbar'

    This function is multi-byte safe.

    RTRIM(str)

    Returns the string str with trailing space characters removed.
以下是代码片段:

mysql> SELECT RTRIM('barbar   ');
        -> 'barbar'

    This function is multi-byte safe.

    TRIM([{BOTH | LEADING | TRAILING} [remstr] FROM] str), TRIM([remstr FROM] str)

    Returns the string str with all remstr prefixes or suffixes removed. If none of the specifiers BOTH, LEADING, or TRAILING is given, BOTH is assumed. remstr is optional and, if not specified, spaces are removed.
以下是代码片段,代码如下:

mysql> SELECT TRIM(' bar   ');
        -> 'bar'
mysql> SELECT TRIM(LEADING 'x' FROM 'xxxbarxxx');
        -> 'barxxx'
mysql> SELECT TRIM(BOTH 'x' FROM 'xxxbarxxx');
        -> 'bar'
mysql> SELECT TRIM(TRAILING 'xyz' FROM 'barxxyz');
        -> 'barx' --phpfensi.com

    This function is multi-byte safe.

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