substr_count
substr_count() returns the number of times the needle substring occurs in the haystack string. Please note that needle is case sensitive.
Note:
This function doesn’t count overlapped substrings. See the example below!
Parameters
The substring to search for
The offset where to start counting. If the offset is negative, counting starts from the end of the string.
The maximum length after the specified offset to search for the substring. It outputs a warning if the offset plus the length is greater than the haystack length. A negative length counts from the end of haystack .
Return Values
This function returns an int .
Changelog
| Version | Description |
|---|---|
| 8.0.0 | length is nullable now. |
| 7.1.0 | Support for negative offset s and length s has been added. length may also be 0 now. |
Examples
Example #1 A substr_count() example
$text = ‘This is a test’ ;
echo strlen ( $text ); // 14
echo substr_count ( $text , ‘is’ ); // 2
// the string is reduced to ‘s is a test’, so it prints 1
echo substr_count ( $text , ‘is’ , 3 );
// the text is reduced to ‘s i’, so it prints 0
echo substr_count ( $text , ‘is’ , 3 , 3 );
// generates a warning because 5+10 > 14
echo substr_count ( $text , ‘is’ , 5 , 10 );
// prints only 1, because it doesn’t count overlapped substrings
$text2 = ‘gcdgcdgcd’ ;
echo substr_count ( $text2 , ‘gcdgcd’ );
?>
See Also
- count_chars() — Return information about characters used in a string
- strpos() — Find the position of the first occurrence of a substring in a string
- substr() — Return part of a string
- strstr() — Find the first occurrence of a string
User Contributed Notes 10 notes
It’s worth noting this function is surprisingly fast. I first ran it against a ~500KB string on our web server. It found 6 occurrences of the needle I was looking for in 0.0000 seconds. Yes, it ran faster than microtime() could measure.
Looking to give it a challenge, I then ran it on a Mac laptop from 2010 against a 120.5MB string. For one test needle, it found 2385 occurrences in 0.0266 seconds. Another test needs found 290 occurrences in 0.114 seconds.
Long story short, if you’re wondering whether this function is slowing down your script, the answer is probably not.
Making this case insensitive is easy for anyone who needs this. Simply convert the haystack and the needle to the same case (upper or lower).
To account for the case that jrhodes has pointed out, we can change the line to:
substr_count ( implode( ‘,’, $haystackArray ), $needle );
array (
0 => «mystringth»,
1 => «atislong»
);
Which brings the count for $needle = «that» to 0 again.
substr_count ( implode( $haystackArray ), $needle );
instead of the function described previously, however this has one flaw. For example this array:
array (
0 => «mystringth»,
1 => «atislong»
);
If you are counting «that», the implode version will return 1, but the function previously described will return 0.
Yet another reference to the «cgcgcgcgcgcgc» example posted by «chris at pecoraro dot net»:
Your request can be fulfilled with the Perl compatible regular expressions and their lookahead and lookbehind features.
$number_of_full_pattern = preg_match_all(‘/(cgc)/’, «cgcgcgcgcgcgcg», $chunks);
works like the substr_count function. The variable $number_of_full_pattern has the value 3, because the default behavior of Perl compatible regular expressions is to consume the characters of the string subject that were matched by the (sub)pattern. That is, the pointer will be moved to the end of the matched substring.
But we can use the lookahead feature that disables the moving of the pointer:
$number_of_full_pattern = preg_match_all(‘/(cg(?=c))/’, «cgcgcgcgcgcgcg», $chunks);
In this case the variable $number_of_full_pattern has the value 6.
Firstly a string «cg» will be matched and the pointer will be moved to the end of this string. Then the regular expression looks ahead whether a ‘c’ can be matched. Despite of the occurence of the character ‘c’ the pointer is not moved.
a simple version for an array needle (multiply sub-strings):
function substr_count_array ( $haystack , $needle ) $count = 0 ;
foreach ( $needle as $substring ) $count += substr_count ( $haystack , $substring );
>
return $count ;
>
?>
Unicode example with «case-sensitive» option;
function substr_count_unicode ( $str , $substr , $caseSensitive = true , $offset = 0 , $length = null ) if ( $offset ) $str = substr_unicode ( $str , $offset , $length );
>
$pattern = $caseSensitive
? ‘~(?:’ . preg_quote ( $substr ) . ‘)~u’
: ‘~(?:’ . preg_quote ( $substr ) . ‘)~ui’ ;
preg_match_all ( $pattern , $str , $matches );
return isset( $matches [ 0 ]) ? count ( $matches [ 0 ]) : 0 ;
>
function substr_unicode ( $str , $start , $length = null ) return join ( » , array_slice (
preg_split ( ‘~~u’ , $str , — 1 , PREG_SPLIT_NO_EMPTY ), $start , $length ));
>
$s = ‘Ümit yüzüm gözüm. ‘ ;
print substr_count_unicode ( $s , ‘ü’ ); // 3
print substr_count_unicode ( $s , ‘ü’ , false ); // 4
print substr_count_unicode ( $s , ‘ü’ , false , 10 ); // 1
print substr_count_unicode ( $s , ‘üm’ ); // 2
print substr_count_unicode ( $s , ‘üm’ , false ); // 3
?>
This will handle a string where it is unknown if comma or period are used as thousand or decimal separator. Only exception where this leads to a conflict is when there is only a single comma or period and 3 possible decimals (123.456 or 123,456). An optional parameter is passed to handle this case (assume thousands, assume decimal, decimal when period, decimal when comma). It assumes an input string in any of the formats listed below.
function toFloat($pString, $seperatorOnConflict=»f»)
$decSeperator=».»;
$thSeperator=»»;
$pString=str_replace(» «, $thSeperator, $pString);
$firstPeriod=strpos($pString, «.»);
$firstComma=strpos($pString, «,»);
if($firstPeriod!==FALSE && $firstComma!==FALSE) if($firstPeriod <$firstComma) $pString=str_replace(".", $thSeperator, $pString);
$pString=str_replace(«,», $decSeperator, $pString);
>
else $pString=str_replace(«,», $thSeperator, $pString);
>
>
else if($firstPeriod!==FALSE || $firstComma!==FALSE) $seperator=$firstPeriod!==FALSE?».»:»,»;
if(substr_count($pString, $seperator)==1) $lastPeriodOrComma=strpos($pString, $seperator);
if($lastPeriodOrComma==(strlen($pString)-4) && ($seperatorOnConflict!=$seperator && $seperatorOnConflict!=»f»)) $pString=str_replace($seperator, $thSeperator, $pString);
>
else $pString=str_replace($seperator, $decSeperator, $pString);
>
>
else $pString=str_replace($seperator, $thSeperator, $pString);
>
>
return(float)$pString;
>