我如何计算字符串中的char并使用PHP进行验证

Make use of substr_count function like this

<?php
 echo substr_count( "B405Q-0123-0600", "-" )."
";
 echo substr_count( "B405Q01230600", "-" )."
";
?>

Will Result

2
0

Validate like this

if(substr_count( $some_string, "-" ) == 2)
{
       echo 'true';
       // do something here
}else
{
       echo 'false validation failed';
       // some error handling
}

If your strings are like shown, then you can do

$re = "/(\\w{5}-\\w{4}-\\w{4})/"; 
$str = "B405Q-0123-0600"; // Your strings
if (preg_match($re, $str, $matches)) {
   // valid
} else {
   // invalid
}

I just need to check if the string is having two hyphens

If you only want to check if there are two hyphens anywhere, then you can split your strings on hyphens. If there are two and only two hyphens, then there will be 3 split parts.

$str = "B405Q-0123-0600"; // your strings
if (count(split("-", $str)) === 3) {
   // two hyphens present
} else {
   // not enough hyphens
}

Try this:

var str = "B405Q-0123-0612";
var arr = str.split("-");

if(arr.length=3){
    alert("Your string contain 2 hyphens");
}

For checking this type of validation you are required to use the Regex of javascript. Use below given regular expression.

var check="^\w+([\s\-]\w+){0,2}$";

Now all need is to check this with creating the javascript function and you are half the way there.

use the below code

  $string = "B405Q-0123-0612";

    $arr = explode("-",$string)

    if (count($arr) == 2)
    {
        //yes you have 2 hyphens
    }

The above procedure is the simplest way to do

preg_match_all("/\-/",'B405Q-0123-0600',$match);
if(count($match[0]) == 2){
  // valid
}else{
  // invalid
}