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Home Backend Development PHP Tutorial utf-8 - php的strlen和mb_strlen结果不同

utf-8 - php的strlen和mb_strlen结果不同

Jun 06, 2016 pm 08:44 PM
gbk php strlen utf-8 Character Encoding

//gbk编码下
$s = '中文测试';
echo mb_strlen($s, 'utf-8'); 
echo strlen(iconv('gbk', 'utf-8', $s));
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1.为什么值不相等
2.strlen 计算的是字符串的字节数还是字符数?
3.mb_strlen 计算的是什么?

回复内容:

//gbk编码下
$s = '中文测试';
echo mb_strlen($s, 'utf-8'); 
echo strlen(iconv('gbk', 'utf-8', $s));
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1.为什么值不相等
2.strlen 计算的是字符串的字节数还是字符数?
3.mb_strlen 计算的是什么?

$s里面有四个宽字符 由于你是gbk环境下的所以占8个字节 如果你把它转成utf-8编码的将会占12个字节
strlen()返回占多少个字节
mb_strlen()返回实际为多少个字符 如果是宽字符的话他会当成长度为一来计算

所以下面的代码

//gbk
$s = '中文测试';
$s_u8 = iconv('gbk', 'utf-8', $s);
var_dump(strlen($s), strlen($s_u8),
         mb_strlen($s, 'gbk'), mb_strlen($s_u8, 'utf-8'));
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结果依次是8,12,4,4

貌似你第二句把编码写错了 但是写错了也能得到一样的结果。。不知道为什么

1.楼主的 mb_strlen()用法是不是有点小问题。 mb_strlen是根据字符串的编码方式来计算字符数。
楼主是否是想用下面的代码:

    <?php
    //gbk编码下
    $s = '中文测试';
    echo mb_strlen($s, 'gbk'); 
    echo mb_strlen(iconv('gbk', 'utf-8', $s), 'utf-8');
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长度都是4,所以首先确保传给mb_strlen的编码方式正确。
2. strlen() 只计算字节数

1、你打印一下,程序的第三行执行了iconv后的$s是乱码的,因为在执行iconv的时候出现了一点错误:Detected an illegal character in input,你把php文件的编码格式改成ANSI就不会出现这个错误。
2、在strlen计算时,对待一个UTF8的中文字符是3个长度
3、在mb_strlen计算时,选定内码为UTF8,则会将一个中文字符当作长度1来计算.

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