PHP和MySQL的删除空白函数介绍

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)

MySQL为:space characters removed

显然,PHP还可以有“other characters”,而且PHP的函数还可以用第二个参数自定义要删除的字符.

对“other characters”，手册解释为,以下是引用片段:

1. ""(ASCII32(0x20)),anordinaryspace.
2. "t"(ASCII9(0x09)),atab.
3. "n"(ASCII10(0x0A)),anewline(linefeed).
4. "r"(ASCII13(0x0D)),acarriagereturn.
5. ""(ASCII0(0x00)),theNUL-byte.
6. "x0B"(ASCII11(0x0B)),averticaltab.

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:

LTRIM(str),Returns the string str with leading space characters removed.

以下是代码片段:

1. mysql>SELECTLTRIM('barbar');
2. ->'barbar'
6. Thisfunctionismulti-bytesafe.
8. RTRIM(str)
10. Returnsthestringstrwithtrailingspacecharactersremoved.

以下是代码片段:

1. mysql>SELECTRTRIM('barbar');
2. ->'barbar'
4. Thisfunctionismulti-bytesafe.
6. TRIM([{BOTH|LEADING|TRAILING}[remstr]FROM]str),TRIM([remstrFROM]str)
8. Returnsthestringstrwithallremstrprefixesorsuffixesremoved.IfnoneofthespecifiersBOTH,LEADING,orTRAILINGisgiven,BOTHisassumed.remstrisoptionaland,ifnotspecified,spacesareremoved.

以下是代码片段,代码如下:

1. mysql>SELECTTRIM('bar');
2. ->'bar'
3. mysql>SELECTTRIM(LEADING'x'FROM'xxxbarxxx');
4. ->'barxxx'
5. mysql>SELECTTRIM(BOTH'x'FROM'xxxbarxxx');
6. ->'bar'
7. mysql>SELECTTRIM(TRAILING'xyz'FROM'barxxyz');
8. ->'barx'--phpfensi.com
10. Thisfunctionismulti-bytesafe.