strstr($a, $b) and strchr() equally , It's also known as , Expression lookup $a For the first time $b, And returns the rest of the string :

.strrchr() From the back to the front, the first one that appears

Just write two lines of code :

$str = 'abc0';
echo strstr($str, '0');//
echo '<hr/>';
echo strstr($str, '0') == '0';//
echo '<hr/>';
// Notice the difference between two equal signs and three equal signs , character string 0 and false It's the same after cast . So when applying To use ===
echo strstr($str, '0') == false; echo '<hr/>'; echo strstr($str, '0') === false;// false
echo '<hr/>'; $str = 'abcabcdefg'; // A very common one substr() and strchr() Combined use , Take what appears after this character
echo substr(strchr($str, 'd'), 1);// efg echo '<hr/>'; // You can do that Of course you have to know 'd’ Is there any , You can judge !==false
echo substr($str, stripos($str, 'd')+1);// efg echo '<hr/>'; // Check the first one from back to front f appear
echo strrchr($str, 'f');// fg

Practice the algorithm , use php Part of the implementation strstr() function , Check whether a string is a substring of another string , A simple test can

* @param $a
* @param $b
* b It's a substring
* a It's full
*/ function str($a, $b){
$alen = strlen($a);
$blen = strlen($b);
for($i=0; $i<= ($alen - $blen); $i++){
if($a[$i] == $b[0]){
$x = $i;
for($j=0; $j< $blen; $j++){
if($b[$j] != $a[$i++]){
$i = $x;
if(intval($j) == $blen){
return true;
} }
return false;

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