php - add string at offset?

Question

If I have a string like "test", I have characters from offset 0-3. I would like to add another string to this one at offset 6. Is there a simple PHP function that can do this?

I am trying this, but getting an error:

PHP Fatal error: Cannot use assign-op operators with overloaded objects nor string offsets in ...

I understand I could concatenate these strings, but I want to build a sentence based on output from Stanford CoreNLP that provides string offset locations http://nlp.stanford.edu/software/example.xml (more info at http://nlp.stanford.edu/software/corenlp.shtml)

$strings[0] = "test";
$strings[1] = "new";

foreach($strings as $string) {

for($i = 0 ; $i <= strlen($string); $i++) {
    print $string[$i];
    if (!isset($sentence)) {
        $sentence = $string[$i];
    }
    else {
        $sentence[strlen($sentence)] .= $string[$i];

    }
    }
}

print_r ($sentence);

PHP docs say at http://www.php.net/manual/en/language.types.string.php

Writing to an out of range offset pads the string with spaces. Non-integer types are converted to integer. Illegal offset type emits E_NOTICE. Negative offset emits E_NOTICE in write but reads empty string. Only the first character of an assigned string is used. Assigning empty string assigns NULL byte.

Did you tried to consider a string as an array of chars? In this way you add charathers or even concatenate strings, where ever you want. — Cristofor
– Cristofor, Commented Jul 8, 2014 at 11:35
the approach is not right, if you want to conseider it as an array you first need to create an array with strlen($yourstring) blocks, so that every block contains a character of your string. — Cristofor
– Cristofor, Commented Jul 8, 2014 at 11:47

Mark · Accepted Answer · 2014-07-08 12:01:56Z

2

Convert the string to an array, in the case where the offset is greater than the string length fill in the missing indexes with a padding character of your choice otherwise just insert the string at the corresponding array index position and implode the string array.

Please see the function below:

function addStrAtOffset($origStr,$insertStr,$offset,$paddingCha=' ')
{
    $origStrArr = str_split($origStr,1);

    if ($offset >= count($origStrArr))
    {
        for ($i = count($origStrArr) ; $i <= $offset ; $i++)
        {
            if ($i == $offset) $origStrArr[] = $insertStr;
            else $origStrArr[] = $paddingCha;
        }
    }
    else
    {
        $origStrArr[$offset] = $insertStr.$origStrArr[$offset];
    }

    return implode($origStrArr);
}

echo addStrAtOffset('test','new',6);

answered Jul 8, 2014 at 12:01

Mark

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Comments

Cristofor · Accepted Answer · 2014-07-08 11:53:27Z

1

To solve your problem first of all you convert your strings in arrays with str_split, then when you've got the array you're done, you can perform any kind of operations on these strings.

Code:

$s1 = "test";
$s2 = "new";
//converting string into array
$strings[0] = str_split($s1, 1);
$strings[1] = str_split($s2, 1);
//setting the first word of sentence
$sentence = $strings[0];
//insert every character in the sentence of "new" word
for ($i=0; $i < count($strings[1]); $i++) { 
    $sentence[] = $strings[1][$i];
}
print_r($sentence);

Result:

Array
(
    [0] => t
    [1] => e
    [2] => s
    [3] => t
    [4] => n
    [5] => e
    [6] => w
)

answered Jul 8, 2014 at 11:53

Cristofor

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1 Comment

giorgio79 Over a year ago

Thanks Cristian. This is a good answer as well! I accepted the other one as the function also allows specifying offset where the string will be added.

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