What are the methods for intercepting php strings?

Method: 1. Use the "substr (string, starting position, interception length)" statement; 2. Use the "mb_substr (string, starting position, interception length, encoding)" statement; 3. Use " mb_strcut (string, starting position, interception length, encoding)" statement; 4. Use the "$str[character position]" statement.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

substr(string, starting position , intercept length)

If the intercepted string is multiple bytes, garbled characters will appear, such as Chinese, suitable for intercepting letters and numbers

$str = 'hello';
echo substr($str,1,2);//输出el

mb_substr( String, starting position, interception length, character encoding)

Suitable for intercepting Chinese, segmented by characters

echo mb_substr('这个真的很nice',0,3,'utf-8'); //输出这个真

mb_strcut(String, starting position, interception Length, character encoding)

Split by bytes

echo mb_strcut('这个真的很nice',0,3,'utf-8'); //输出这

$str[0]

Treat strings as characters Collection, Chinese is not applicable!

$str = 'hello';
echo $str[0];//输出h

Sometimes the string contains Chinese and English numbers, etc., so customize a function that does not distinguish between Chinese and English to split the string

/**
* 
* 中英混合的字符串截取
* @param 待截取字符串 $sourcestr
* @param 截取长度 $cutlength
*/
function sub_str($sourcestr, $cutlength) {
	$returnstr = '';//待返回字符串
	$i = 0;
	$n = 0;
	$str_length = strlen ( $sourcestr ); //字符串的字节数 
	while ( ($n < $cutlength) and ($i <= $str_length) ) {
		$temp_str = substr ( $sourcestr, $i, 1 );
		$ascnum = Ord ( $temp_str ); //得到字符串中第$i位字符的ascii码 
		if ($ascnum >= 224) {//如果ASCII位高与224，
			$returnstr = $returnstr . substr ( $sourcestr, $i, 3 ); //根据UTF-8编码规范，将3个连续的字符计为单个字符  
			$i = $i + 3; //实际Byte计为3
			$n ++; //字串长度计1
		} elseif ($ascnum >= 192){ //如果ASCII位高与192，
			$returnstr = $returnstr . substr ( $sourcestr, $i, 2 ); //根据UTF-8编码规范，将2个连续的字符计为单个字符 
			$i = $i + 2; //实际Byte计为2
			$n ++; //字串长度计1
		} elseif ($ascnum >= 65 && $ascnum <= 90) {//如果是大写字母，
			$returnstr = $returnstr . substr ( $sourcestr, $i, 1 );
			$i = $i + 1; //实际的Byte数仍计1个
			$n ++; //但考虑整体美观，大写字母计成一个高位字符
		}elseif ($ascnum >= 97 && $ascnum <= 122) {
			$returnstr = $returnstr . substr ( $sourcestr, $i, 1 );
			$i = $i + 1; //实际的Byte数仍计1个
			$n ++; //但考虑整体美观，大写字母计成一个高位字符
		} else {//其他情况下，半角标点符号，
			$returnstr = $returnstr . substr ( $sourcestr, $i, 1 );
			$i = $i + 1; 
			$n = $n + 0.5; 
		}
	}
	return $returnstr;
}

Recommended learning: "PHP Video Tutorial》

The above is the detailed content of What are the methods for intercepting php strings?. For more information, please follow other related articles on the PHP Chinese website!