PHP only replaces the first occurrence of a string

PHP only replaces the first occurrence of a string_PHP Tutorial

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Release： 2016-07-13 16:57:27

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In PHP, when we want to replace specified characters in a string, we usually replace them all at once, such as the str_replace function, but sometimes we only want to replace the first occurrence, such as replacing keywords in an article. This cannot appear if there are 100 of them. 100 times, I just want to limit it a few times. Let me introduce to you how to achieve it.

Example

$str='This is a string. I only replace ABC once and I don’t replace the following ABC. Is there any way to achieve this? ';

Replace the first abc with xyz. Since the string to be replaced is fixed, many people think of using the str_replace() function to see if the use of this function is what we want

str_replace( mixed $search , mixed $replace , mixed $subject [, int &$count ] )

I accidentally thought that was what we wanted. The last parameter is to return the total number of replacements. It is a reference variable, not what I want to specify how many times it will be replaced, so use str_replace( ) is not possible

preg_replace() can be implemented, but it’s a pity that regular expressions are used,

The code is as follows

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代码如下	复制代码
$str=preg_replace('/abc/','abc',$str,1); echo $str;

$str=preg_replace('/abc/','abc',$str,1);
echo $str;

Example

Display email as starting from the first 2 digits of @ (inclusive) and hiding 4 digits forward

代码如下

复制代码

有没有不用正则的，嗯可以这样

$replace='xyz';
if(($position=strpos($str,$replace))!==false){
$leng=strlen($replace);
$str=substr_replace($str,'abc',$position,$leng);
}
echo $str;

The code is as follows

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If I want to replace to a specified number of times, please refer to the following method

/*
* $text is the input text;
* $word is the original string;
* $cword is the string that needs to be replaced;
* $pos refers to the position where $word appears for the Nth time in $text, counting from 1
* */
function changeNstr($text,$word,$cword,$pos=1){
$text_array=explode($word,$text);
$num=count($text_array)-1;
if($pos>$num){
return "the number is too big!or can not find the $word";
}
$result_str='';
for($i=0;$i<=$num;$i++){
if($i==$pos-1){
$result_str.=$text_array[$i].$cword;
}else{
$result_str.=$text_array[$i].$word;}

The code is as follows

代码如下

复制代码

/*
* $text是输入的文本；
* $word是原来的字符串；
* $cword是需要替换成为的字符串；
* $pos是指$word在$text中第N次出现的位置，从1开始算起
* */
function changeNstr($text,$word,$cword,$pos=1){
$text_array=explode($word,$text);
$num=count($text_array)-1;
if($pos>$num){
return "the number is too big!or can not find the $word";
}
$result_str='';
for($i=0;$i<=$num;$i++){
if($i==$pos-1){
$result_str.=$text_array[$i].$cword;
}else{
$result_str.=$text_array[$i].$word;}

}

return rtrim($result_str,$word);
}
$text='hello world hello pig hello cat hello dog hello small boy';
$word='hello';
$cword='good-bye';
echo changeNstr($text,$word,$cword,3);
//输出：hello world hello pig good-bye cat hello dog hello small boy
?>

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}

return rtrim($result_str,$word);
}
$text='hello world hello pig hello cat hello dog hello small boy';
$word='hello';
$cword='good-bye';
echo changeNstr($text,$word,$cword,3);
//Output: hello world hello pig good-bye cat hello dog hello small boy
?>

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http: //www.bkjia.com/PHPjc/631531.htmlTechArticleTo replace specified characters in a string in php, we usually replace them all at once, such as the str_replace function, but sometimes we just want Replace the first occurrence, like replacing the keywords of the article. If there is...