CODEWITHSUNDEEP
phpstringvariablessubstringlimit
dave
dave

Reputation: 15459

Insert substring right before first occurrence of another string

Take for example these strings:

  $strOne = "Place new content here:  , but not past the commma.";
  $strTwo = "test content";

So based on the strings above, how do make a new string that looks like this:

  $finalstr = "Place new content here:  test content, but not past the comma.";

EDIT

Also, lets assume I don't have access to $strOne, meaning I want to modify it via string functions not directly the string via concatenation etc...

Upvotes: 1

Views: 1139

Answers (5)

Marcelo Machado
Marcelo Machado

Reputation: 1397

You can split the first string by comma and then concat in the way you want. To split you may use explode method:

$strArray = explode(',', $strOne, 2);
$finalstr = $strArray[0].$strTwo.",".$strArray[1];

Upvotes: 4

mickmackusa
mickmackusa

Reputation: 47894

str_replace() does not have the capability to limit the number of replacements. preg_replace() though not necesary for finding your needle in the haystack string DOES allow replacement limiting. Using explode() is not a horrible approach, but you should limit the explosions to 2 if you use it. I do not like the indirect-ness of generating a temporary array when a string result is sought.

Code: (Demo)

$strOne = "Place new content here:  , but not past the commma.";
$strTwo = "test content";

echo preg_replace('/,/', "$strTwo,", $strOne, 1);

You could use preg_replace('/(?=,)/', $strTwo, $strOne, 1) to avoid mentioning the needle in the replacement string, but that regex will perform worse because the lookahead will be performed on every step while traversing the haystring string -- not great.

If your needle string might contain characters that have special meaning to the regex engine, then use '/' . preg_quote($yourNeedle, '/') . '/' as your pattern.

If your needle is more variable, then use the same regex technique. If wanting to find the first hashtag substring in a block of text, merely search for the first occurring # followed by one (or more) word character(s). If you want to enforce that the # is preceded by a space, you can add that too. You can use a lookahead to avoid copying the needle into the replacement parameter but this might execute a little slower depending on the quality of the haystack string.

Input:

$strOne = "Programming requires life long learning #learning #stackoverflow #programming";
$strTwo = "\n\n";

Code: (Demo)

echo preg_replace('/#\w/', "$strTwo$0", $strOne, 1);
// or echo preg_replace('/ (#\w)/', "$strTwo$1", $strOne, 1); // to replace the preceding space with 2 newlines

Or: (Demo)

echo preg_replace('/ \K(?=#\w)/', $strTwo, $strOne, 1);

Upvotes: 0

Bastian Bräu
Bastian Bräu

Reputation: 791

$finalstr = str_replace(',', $strTwo.',', $strOne, 1);

Upvotes: -2

Maximus2012
Maximus2012

Reputation: 1819

Try a combination of strpos and substr_replace ?

$strOne = "Place new content here:  , but not past the commma.";
$strTwo = "test content";

// find the position of comma first
$pos = strpos($strOne, ',');
if ($pos !== false)
{
     // insert the new string at the position of the comma
     $newstr = substr_replace($strOne, $strTwo, $pos, 0);
     var_dump($newstr);
}

Output:

string(63) "Place new content here: test content, but not past the commma."

Upvotes: 3

anotherdev
anotherdev

Reputation: 2569

With your first example:

$strTwo = "test content";
$strOne = "Place new content here: $strTwo, but not past the commma.";

To go further: use an array of string, and create a function which returns the concatenations of the strings.

Upvotes: -2

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