用环绕式PHP从字符串中获取X个字符

Question

I have a PHP problem where I have a string of numbers:

ie/ 1,2,3,4,5,6,7,8,9...... X

I know the first number and have to create a string X long so that it wraps around

for example if my string is 1,2,3,4,5 and my first number is 4 - i need to return the string:

4,5,1,2,3

I'd like to create a function to achieve this - any help would be great!

Thanks.

Answer 1

<?php
function MyWrap($string, $first)
{
    $splitHere = strpos($string, $first);
    return rtrim(substr($string, $splitHere).','.substr($string, 0, $splitHere), ',');
}

echo MyWrap('1,2,3,4,5', '4');
?>

Output:

4,5,1,2,3

Answer 2

function wrapAroundNeedle($myString, $myNeedle)
{
  $index = strrpos($myString, $myNeedle);
  return substr($myString, $index).",".substr($myString, 0, $index - 1);  
}

How to roll your own. Note that strrpos only allows single characters for $needle in php 4.

string substr ( string $string , int $start [, int $length ] )

int strrpos ( string $haystack , string $needle [, int $offset = 0 ] )

http://php.net/manual/en/function.substr.php

http://php.net/manual/en/function.strrpos.php

Answer 3

$pos = strpos($string,$first_number);
return substr($s,$pos).','.substr($s,0,$pos);

Answer 4

I believe I understand what you need - try this:

function numsWrap($firstNumber, $total) {
  $newStr = "";

  $inc = $firstNumber;
  for($i = 0; $i < $total+1; $i++) {
    if($i == 0) {
      $newStr .= $inc;
    } else {
      if($inc == $total) {
    $newStr .= "," . $inc;

    $inc = 0;
      } else {
    $newStr .= "," . $inc;
      }
    }

    $inc++;
  }

  return $newStr;
}

Usage:

echo numsWrap(5, 10);
5,6,7,8,9,10,1,2,3,4,5