trim()

(PHP 4, PHP 5, PHP 7)

去除字符串首尾处的空白字符（或者其他字符）

说明

此函数返回字符串$str去除首尾空白字符后的结果。如果不指定第二个参数，trim()将去除这些字符：

• ""(ASCII32(0x20))，普通空格符。
• "t"(ASCII9(0x09))，制表符。
• "n"(ASCII10(0x0A))，换行符。
• "r"(ASCII13(0x0D))，回车符。
• "0"(ASCII0(0x00))，空字节符。
• "x0B"(ASCII11(0x0B))，垂直制表符。

参数

待处理的字符串。

可选参数，过滤字符也可由$character_mask参数指定。一般要列出所有希望过滤的字符，也可以使用“..”列出一个字符范围。

返回值

过滤后的字符串。

范例

Example #1trim()使用范例

以上例程会输出：

string(32) "        These are a few words :) ...  "
string(16) "    Example string
"
string(11) "Hello World"
string(28) "These are a few words :) ..."
string(24) "These are a few words :)"
string(5) "o Wor"
string(14) "Example string"

使用trim()清理数组值

以上例程会输出：

array(3) {
  [0]=>
  string(5) "apple"
  [1]=>
  string(7) "banana "
  [2]=>
  string(11) " cranberry "
}
array(3) {
  [0]=>
  string(5) "apple"
  [1]=>
  string(6) "banana"
  [2]=>
  string(9) "cranberry"
}

注释

Becausetrim()trims characters from the beginning and end of astring, it may be confusing when characters are (or are not) removed from the middle.trim('abc','bad')removes both 'a' and 'b' because it trims 'a' thus moving 'b' to the beginning to also be trimmed. So, this is why it "works"whereastrim('abc','b')seemingly does not.

参见

• ltrim() 删除字符串开头的空白字符（或其他字符）
• rtrim() 删除字符串末端的空白字符（或者其他字符）
• str_replace() 子字符串替换

It may be useful to know that trim() returns an empty string when the argument is an unset/null variable.

When specifying the character mask, 
make sure that you use double quotes

Here is the output:
----------------------------TRIMMED OK:
Hello World
----------------------------TRIMMING NOT OK:
   Hello World
----------------------------

Non-breaking spaces can be troublesome with trim: 

trim is the fastest way to remove first and last char.
Benchmark comparsion 4 different ways to trim string with '/' 
4 functions with the same result - array exploded by '/'

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