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Strpos () inside while loop never ends

There is a line

$ string = 'Foo, Bar, Test,';

All I want to do is count the number of commas inside the string.

But everything leads to an endless while loop.

So I tried # 1:

$ count = 0;

while($pos = strpos($string, ',') !== FALSE){
    $count++;
    // Never ends
}

And also # 2,

while(true){
  if ( strpos($string, ',') !== FALSE ){
     $count++;
  } else {
    break;
  }
}

Both of them never end. Where is the problem?

+3


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4 answers


You can simply use substr_count()

:

substr_count($string, ',');

Your code strpos()

requires a third parameter to start the search at a specific offset, for example:

strpos($string, ',', 12); // start searching from index 12

It doesn't work like an iterator. Something like this will work:



$start = 0;
while (($pos = strpos($string, ',', $start)) !== FALSE) {
  $count++;
  $start = $pos + 1;
}

Update

If you want some real fantasy:

class IndexOfIterator implements Iterator
{
  private $haystack;
  private $needle;

  private $start;
  private $pos;
  private $len;
  private $key;

  public function __construct($haystack, $needle, $start = 0)
  {
    $this->haystack = $haystack;
    $this->needle = $needle;
    $this->start = $start;
  }

  public function rewind()
  {
    $this->search($this->start);
    $this->key = 0;
  }

  public function valid()
  {
    return $this->pos !== false;
  }

  public function next()
  {
    $this->search($this->pos + 1);
    ++$this->key;
  }

  public function current()
  {
    return $this->pos;
  }

  public function key()
  {
    return $this->key;
  }

  private function search($pos)
  {
    $this->pos = strpos($this->haystack, $this->needle, $pos);
  }
}

foreach (new IndexOfIterator($string, ',') as $match) {
  var_dump($match);
}
+4


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Try the following:

$text = 'Foo, Bar, Test,';
echo substr_count($text, ',');


ref: http://php.net/manual/en/function.substr-count.php

+2


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strpos()

returns the first occurrence $needle

, so if you don't specify another $offset

, you always get the same result, thus an infinite loop.

If you insist on using strpos()

, try this:

$pos=0;
while(($pos = strpos($string, ',',$pos)) !== FALSE){
    $count++;
    $pos++;
    // This ends
}

You can use substr_count()

to simplify the task.

Edit

demo version

+2


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Or try if substr_count doesn't work:

$pos = -1;
$count=0;
while( $pos = strpos($in, ',', $pos+1) !== FALSE){
     $count++;
     }

I have not tested, you absolutely have to! == FALSE. If you're using mb_strpos, you don't.

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