PHP：在字符串中每4个字符替换3个字符

Question

I have a string and I want to know how can I keep 1 character in a 4 character interval.

$string = "bc7yad3odf0x"; // and goes like this..

I want my new string to be:

yox

which comes out of bc7 y ad3 o df0 x

The three characters to be ommited are always like char-char-number.

EDIT: Thank you all for answering. I tested all your answers and they work fine for me, except trisweb's preg_replace() solution, where I get "Unknown modifier 'g'". I accept Bhavik Shah's answer since I think is the simplest to my understanding.

Answer 1

只是它

preg_replace("/\w{3}(\w)/","$1",$string);

Answer 2

$nstr = "";
$str_array = array();

//split string in chunks of 4-char strings
$str_array = str_split($string, 4);

//loop through all elements of array and take the required character
foreach($str_array as $key => $value){
    $nstr .= $value[3];
}
echo $nstr;

More details about str_split .

Answer 3

$str = "bc7yad3odf0x";
$final_str = "";
$len = strlen($str);

for($i = 3; $i < $len; $i = $i+4) {
    $final_str .= substr($str, $i, 1)." ";
}

echo $final_str;

Answer 4

$newString = implode(
    '',
    array_map(
        function($value) {
            return substr($value,-1);
        },
        str_split($string,4)
    )
);

Answer 5

$string = "bc7yad3odf0x";
$new_string = "";
$iterations = ceil(strlen($string)/4);

for ($i=1;$i <= $iterations; $i++)
{
    $new_string .= substr($string, $i*4-1, 1);
}

print $new_string;

Answer 6

Seems like a job for a regular expression!

$kept = preg_replace('/[a-z]{2}[0-9]/gi', "", $string);

What we're doing here is replacing occurrences of the kind "letter-letter-number" with a blank string, removing them.

If the string is always of the form you say, then it should work fine. However, if you always simply want the 4th character kept, you could use:

$kept = preg_replace('/.{3}(.)/gi', "$1", $string);

Or, to use a similar idea of using backreferences to make the first form more strict, use:

$kept = preg_replace('/[a-z]{2}[0-9](.)/gi', "$1", $string);

For more on using regular expressions in PHP, see this nice article.

Answer 7

in php you can access string like arrays

example:

$text = "abcde";
echo $text[1]; // b

so you could take every forth character and concatenate it to your final string. That is the easiest way i can think of at the moment.

Answer 8

Better use regex:

$var = "bc7yad3odf0x";

$var = preg_replace("/[a-z]{2}[0-9]([a-z])/i","$1",$var);

echo $var;

$var = "bc7yad3odf0x";

$var = preg_replace("/[a-z]{2}[0-9]/i","",$var);

echo $var;

Answer 9

Try this

$y = 3;
for($i=0; $i<strlen($string); $i++){
    if($y < strlen($string)){
        $out .= substr($string,$y,1);
        $y = $y+4;
    }else{
        break;
    }
}
echo $out;

Answer 10

It's easy for-loop

$ans = "";
for($i = 3, $l = strlen($s); $i < $l; $i += 4)
    $ans .= $s[$i];