Write a program in PHP to implement the following functions

Write a program to implement the following functions:

a. How to determine whether a character exists in a string

echo strstr('abcdefgcd'  , 'cd');
 echo strpos('ab0defgcd'  , 'cd');

Example:

<?php
$str = &#39;abcdef&#39;;
$find   = &#39;abc&#39;;
$pos = strpos($mystring, $findme);

// 注意这里使用的是 ===不能使用==
// 因为如果没有字符串 就返回false，如果这个字符串位于字符串的开始的地方，就会返回0为了区分0和false就必须使用等同操作符 === 或者 ！==
if ($pos === false) {
    echo "$find不在$str中";
} else {
    echo "$find在$str中";
}
?>

<?php
$string = &#39;abcdef abcdef&#39;;
$find = strpos($string,&#39;a&#39;,1); // $find = 7, 不是 0
?>

b. How to determine a string How many times does a character appear in?

echo substr_count('abcdefgcd'  , 'cd');

Example:

<?php
$str = &#39;fdafdasfsfwrewonvxzf&#39;;
$count = Array();
$len = strlen($str);
for($i=0; $i<$len; $i++)
{
$v = substr($str, $i, 1);
$count[$v]++;
}
print_r($count);
?>

c. How to remove the last character of a string

echo substr('abcdefgcd'  , 0 ,  -1);

Example:

$str = "1,2,3,4,5,6,"; 
$newstr = substr($str,0,strlen($str)-1); 
echo $newstr; 
//echo 1,2,3,4,5,6

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