Character index in a String

MattFaus

Ok, how can I insert something in between the 45th and 46th characters of a string? Assuming there is one. Also, I don't know what the 45th and 46th characters are (dynamically changed), but it is always the 45th and 46th character.

Basically, I need to know how to break a string into an array with each character in it's own element.

craig34

It's not exactly the solution that you're looking for, but you could always do the following:

$string = "this should have more than 46 characters";
$length = strlen($string);
$first_half = substr($string, 0, 45);
$second_half = substr($string, 46, $length);

$new_string = $first_half . "your new stuff" . $second_string;

Like I said, not the most elegant piece of code, but functional.

drew010

$string = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
// the second s is the 45th character

$firstPart = substr($string,0,45);
//makes firstPart = string starting at character 0 up to char 45.

$secondPart = substr($string,46,strlen($string));
//makes secondPart = string starting at char 46 up to the last char

$inserted = $firstPart . "text_between_45th_&_46th" . $secondPart;

that will insert whatever you want between the 45th and 46th character...if you want to break every letter up into its own array element do this.

$string = "abcdefghijklmnopqrstuvwxyz";
$chars = preg_split('//', $string, -1, PREG_SPLIT_NO_EMPTY);

print_r($chars);

that will make every character in $string its own array element of $chars

dalecosp

originally posted by MattFaus
Basically, I need to know how to break a string into an array with each character in it's own element.

while ($x<strlen($string)) {
   $myarray[$x]=$string[$x];
   $x++;
   }

MattFaus

Do you have to declare arrays any special way?

Normal variable:

$normal;

Array?

$array = array();

If your not going to put in the elements until later, do you have to tell the compiler that the variable WILL be an array?

(It's almost there, thanks for the help!)

MattFaus

Hmmmm, from your code it seems that strings are automatically considered arrays, is this true?

If so, I don't need to break each character into it's own element, I can just reference it with the [] index.

drew010

in the case of PHP, there is no compiler, it runs the scripts from the source code, you dont have to compile them, if you want to make a variable an array the will be used later you can do
$variable = array(); //creates an empty array with name $variable.

but you can also do
$variable = array("one","two","something_else");

however, if you try to do
array_push($array_name,"value");
without declaring $array_name as an array, it will give you an error.

php is not strict when it comes to declaring variables and the data-type of the variables like C/C++ and some other languages are.

laserlight

Yes, strings are considered arrays of characters.
In PHP this probably isnt quite the case (and arrays arent really arrays either), so you should use {} instead of [] for string indices.

drew010

Originally posted by MattFaus
Hmmmm, from your code it seems that strings are automatically considered arrays, is this true?

If so, I don't need to break each character into it's own element, I can just reference it with the [] index.

a string is basically an array of char variables.
for example in C the following code will look familiar
const char varname[] = "abcdef";

where char is a one byte variable...strings in php can be accessed using an array form $string[3].

james2010

Forget dealing with arrays on this one, you can easily place a character or string at any position with substr_replace()

for example to place something between the 45th and 46th character use


$str = substr_replace($str, "text to add", 45, 0);

MattFaus

Ok, found out that I need to insert something for every 45th character. Example:

"45 characters" . $something . "45 more characters" . $something . "45 more characters"

I need to do it for several strings, and they will be of all different lengths.

laserlight

hmm... for a moment I thought you were suggesting str_replace() :o

but yeah, substr_replace() should be able to do it better, never used it so I didnt consider it.

laserlight

The 45th character is at index 44
The next 45th character is at index 44 + 45 = 93

as such,

$string = "... the string ...";
for ($i = 44; $i < $len; $i += 45)
	$string = substr_replace($string, $something, $i, 0);

james2010

Well be careful when doing this because the string is constantly changing length, something like this might work for you..

(not tested)


$str = "... something ... ";
$something = "text to add";
$len = strlen($str);

$len2 = 0;
for($i = 44; $i<$len; $i += (45+$len2)) {
  $str = substr_replace($str, $somthing, $i, 0);
  $len2 = strlen($something);
  $len += $len2;
}

laserlight

I've tested, and james2010's method should actually be:

<?php
$str = "... some string ...";
$something = "something";
$len = strlen($str);
$offset = 45; //number of characters to skip
$len2 = strlen($something);

for($i = $offset; $i < $len; $i += $len2 + $offset) {
	$str = substr_replace($str, $something, $i, 0);
	$len += $len2;
}
echo $str;
?>

If we were to go back to the earlier suggestions of using substr(), then use:

<?php
$string = "... some string";
$len = strlen($string);
$offset = 45; //the number of characters to skip
$something = "something";

$result = '';
for ($i = 0; $i < $len; $i += $offset) {
	$result .= substr($string, $i, $offset);
	//only add between the nth and (n+1)th chars
	if ($i + $offset < $len)
		$result .= $something;
}
echo $result;
?>

Weedpacket

$string = "Et cetera, et cetera...";
$something = 'something';
$result = chunk_split($string, 45, $something);
echo $result;

PHP's got some nice string-handling functions, hasn't it?

dalecosp

Originally posted by drew010
however, if you try to do array_push($array_name,"value");
without declaring $array_name as an array, it will give you an error.

php is not strict when it comes to declaring variables and the data-type of the variables like C/C++ and some other languages are.

You are correct that PHP is "weakly typed," but in my example, $array_name is assumed an array, and no errors will be produced by using array operators on the array. You might even say that PHP is "intuitively typed."

$string="The truth will make you free";

while ($x<strlen($string)) {
   $myarray[$x]=$string[$x]." ";
   $x++;
   }

array_push($myarray, "!");
foreach ($myarray as $t) {
   echo $t;
// No errors...OTOH...
array_push($string, "!");
//produces "Warning: first argument to array_push() should be an array"
   }

Now, there's little point to arguing about it ... the OP asked a specific question, I gave a correct answer - typical geek response. 😃

Generally, converting strings to arrays for manipulation is not necessary and is a kludge. There are two great suggestions in this thread, and they should be used. However, it is trivial to do, since you can index a string "as if" it were an array 🙂

drew010

the last example will work because strings are arrays. im saying for example...
you have php code
and then this line of code:

array_push($somevar,"data"); //$somevar has not been initialized before this line.

that will produce an error...

for more detailed information on strings see http://php.net/manual/en/language.types.string.php

dalecosp

the last example will work because strings are arrays

Which example? And what version of PHP?

My code was tested, and the error given is what it will produce. The string var $string was already established...

for more detailed information on strings see http://php.net/manual/en/language.types.string.php

Strings may be held in an array-like manner, but they are not arrays. The page you cite says this:

A string is a series of characters.

Now, there are a lot of similarities between a duck and a goose, but they're not the same critter. Same thing goes here. You can index a string in the same way you index an array. You can't use array_push() on a string---unless they've changed this in a more recent release of PHP...

And logically, if strings and arrays are the same thing, why are they defined seperately and have two different sets of functions for manipulating them?