PHP determines whether a string contains the specified string

php determines whether a string contains the specified string:

1. strstr

strstr() function searches for a string in another string appears for the first time in .
This function returns the rest of the string (from the matching point). Returns false if the searched string is not found.

The code is as follows:

<?php
 /*如手册上的举例*/
 $email = &#39;user@example.com&#39;;
 $domain = strstr($email, &#39;@&#39;);
 echo $domain;
 // prints @example.com
?>

2. stristr

stristr() function finds the first occurrence of a string in another string.
If successful, return the remainder of the string (from the point of the match). If the string is not found, returns false.

It is used exactly the same as strstr. The only difference is that strstr is not case-sensitive.

3. strpos

The strpos function returns a boolean value. FALSE and TRUE are not used Say more. Use "===" to judge. strpos is faster than the above two functions in terms of execution speed. In addition, strpos has a parameter to specify the judgment position, but the default is empty. It means to judge the entire string. The disadvantage is that it is Chinese support is not good.

Example 1

if(strpos('www.jb51.net','jb51') !== false){ 
 echo '包含jb51'; 
}else{
 echo '不包含jb51'; 
}

Example 2

$str= 'abc';
$needle= 'a';
$pos = strpos($str, $needle); // 返回第一次找到改字符串的位置，这里返回为1，若查不到则返回False

4. explode

Use explode to judge the PHP judgment string containing code As follows:

function checkstr($str){
 $needle ='a';//判断是否包含a这个字符
 $tmparray = explode($needle,$str);
 if(count($tmparray)>1){
 return true;
 } else{
 return false;
 }
}

5. substr For example, we need to determine whether the last character is a specified character

<?php
/*
$str1="<p>这是个winrar专用的dll然后下哦啊不错的dll文件，QlogWin32.dll</p>";
if(substr($str1,-8)==".dll</p>"){
echo substr($str1,0,-4);
}

6. substr_count counts the number of times "substring" appears in the "original string"

The substr_count() function is the number of times a small string appears in a large string:

$number = substr_count(big_string, small_string);

function check_str($str, $substr)
{
 $nums=substr_count($str,$substr);
 if ($nums>=1)
 {
  return true;
 }
 else
 {
  return false;
 }
}

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