plz help how do i create my own functions??

[loudog]

Hey guy's I want you to write custom php functions which behaves like the

built-in ones. What is the best way to learn how to write you're own functions??

[fugix]

I suggest you look here

[loudog]

wow.. simple answers like that  make me feel so dumb for asking questions like that .lol  I guess that's the process you go thru to learn  valuable skill in life. Like they once told me your not nosy you will never learn.lol 

 

 

ps....thanks to everyone in advance for having such patience with noob like me.

[fugix]

No problem at all. 

The manual that I referred you to will teach you alot about many different features that php has to offer

[loudog]

hey guys, I just got an assignment which im having alot of trouble with and i was hoping that you guy's could help me.

The assignment is that i must write my own functions. I've read the php manual and yes i do understand how to write a function but im not very good at writing my own this is my first time and what makes it worst is that i can't copy someone else function i have to write my own.

 

In this assignment you will have to

rewrite some of the built-in functions. For example: If I ask you

rewrite the function strrev() (strrev reverses a given string),you can

do something like this:

 

function dan_strrev($input) {

 

    $i = 0;

    $myLen = 0;

 

    while (true) {

        if (isset($input[$i])) {

            $myLen = $myLen + 1;

            $i = $i + 1;

        }

        else {

            break;

        }

    }

 

    $temp = '';

    for ($i = $myLen - 1; $i >= 0; $i--) {

        $temp = $temp.$input[$i];

    }

    return $temp;

}

 

echo dan_strrev('Hello');

echo strrev('Hello');

 

So, you can see that both the built-in function strrev() as well as

the one we wrote (dan_strrev()) gives the same output.

 

Please do the same for the following built-in functions:

1).str_pad — Pad a string to a certain length with another string

 

2).str_split — Convert a string to an array

 

3).str_repeat — Repeat a string

 

4).array_combine — Creates an array by using one array for keys and

another for its values

 

5).array_flip — Exchanges all keys with their associated values in an array

 

6).array_pop — Pop the element off the end of array

 

7).array_udiff_assoc — Computes the difference of arrays with

additional index check, compares data by a callback function

 

.array_walk — Apply a user function to every member of an array

 

9).array_uintersect — Computes the intersection of arrays, compares

data by a callback function

 

10).usort — Sort an array by values using a user-defined comparison function

 

11).array_flip — Exchanges all keys with their associated values in an array

 

12).ksort — Sort an array by key

 

13).in_array — Checks if a value exists in an array

 

14).array_search — Searches the array for a given value and returns

the corresponding key if successful

 

15).array_merge — Merge one or more arrays

 

If you want to know how these functions,please take a look at the php

manual/documentation on php.net.

 

Email me if you have not understood anything that I have explained so

far. I am not setting a deadline but it will be good if you can

complete this in the next 2 weeks

 

[gizmola]

Yes, looks like you have your work cut out for you, your teacher is tough.  The php manual is very nice, you can go to the manual page of any function by adding the name to the php.net url.  Read the description of the functions and then start writing your code.  I can give you a tip, since a lot of these are string related, and that is that a php string is also an array of characters.

 

Try:

$str = 'This is a test string';
echo $str[3];

echo '
';

$strlength = strlen($str);
for ($x=0; $x   echo "Character $x = $str[$x] 
"
}

 

You can go through an array using foreach(). 

 

Good luck, and the only way to learn is to dive into it.

[loudog]

its not so much the the function but what type of argument should i use that gets me confuse in this assignment. i don't know if i use and if statement,while loop,or , foreach. I look at the examples the they have in php manaul and it  just makes me feel even more  lost :-\ 

 

 

 

[gizmola]

You need to replicate the behavior of the functions with php code.  So you need the same arguments, and your task is to figure out how to match the behavior.  Start with str_pad

[loudog]

that's the problem  that idk what statement should i use. should i use the if,while, or foreach. im lost and the teacher won't except a reuse of  the php net example even if i change the name  or the variable. am i missing the point??

 

this is the php manual example

<?php

$input = "Alien";

echo str_pad($input, 10);                      // produces "Alien    "

echo str_pad($input, 10, "-=", STR_PAD_LEFT);  // produces "-=-=-Alien"

echo str_pad($input, 10, "_", STR_PAD_BOTH);  // produces "__Alien___"

echo str_pad($input, 6 , "___");              // produces "Alien_"

?>

 

[gizmola]

Here's the key part of the manual:

 

string str_pad ( string $input , int $pad_length [, string $pad_string = " " [, int $pad_type = STR_PAD_RIGHT ]] )

 

This functions returns the input string padded on the left, the right, or both sides to the specified padding length. If the optional argument pad_string is not supplied, the input is padded with spaces, otherwise it is padded with characters from pad_string up to the limit.

 

You might ask him if you need to match every option, because some of those functions have a lot of flexibility.  As you can see this defaults to taking 2 parameters, so your function needs to start with those 2, and you need to implement it.  Assuming you need complete replication, you have 2 default parameters you need to define in your function. 

 

function my_str_pad($input, $length, $padchar = ' ', $location = STR_PAD_RIGHT) {
  // now you need to start coding it.
  $inputLen = strlen($input);
  $padsize = $length - $inputLen;
  if ($padsize > 0) {
     switch ($location) {
        case STR_PAD_BOTH :
          break;
        case STR_PAD_LEFT :
          break;
        default:
          // STR_PAD_RIGHT
          $repeat = ceil($padsize / strlen($padchar));
          $t = $input;
          for ($x=0; $x               $t .= $padchar;
     }
      return substr($t, 0, $length);
  } else {
     return $input;
  }

}

 

That should be a good start for you.  As you can see i threw in one of the 3 cases, albeit probbly the easiest one.  It also occurs to me that there is a better way to handle the padding string -- figure that out seperately and concat it at the very end when you return it, would be better.  At any rate, flesh it out, and you have an idea how to approach the rest of these. Fair warning, there could be problems but with this, it's all off the top of my head, but at least it should give you an idea how you should start approaching the process of coding these.

[loudog]

function my_str_pad($input, $length, $padchar = ' ', $location = STR_PAD_RIGHT) {

  // now you need to start coding it.

  $inputLen = strlen($input);

  $padsize = $length - $inputLen;

  if ($padsize > 0) {

    switch ($location) {

        case STR_PAD_BOTH :

          break;

        case STR_PAD_LEFT :

          break;

        default:

          // STR_PAD_RIGHT

          $repeat = ceil($padsize / strlen($padchar));

          $t = $input;

          for ($x=0; $x < $repeat; $x++)

              $t .= $padchar;

    }

      return substr($t, 0, $length);

  } else {

    return $input;

  }

function my_str_pad($input, $length, $padchar = ' ', $location = STR_PAD_RIGHT) {

  // now you need to start coding it.

  $inputLen = strlen($input);

  $padsize = $length - $inputLen;

  if ($padsize > 0) {

    switch ($location) {

        case STR_PAD_BOTH :

          break;

        case STR_PAD_LEFT :

          break;

        default:

          // STR_PAD_RIGHT

          $repeat = ceil($padsize / strlen($padchar));

          $t = $input;

          for ($x=0; $x < $repeat; $x++)

              $t .= $padchar;

    }

      return substr($t, 0, $length);

  } else {

    return $input;

  }

 

}

 

 

That should be a good start for you.  As you can see i threw in one of the 3 cases, albeit probbly the easiest one.  It also occurs to me that there is a better way to handle the padding string -- figure that out seperately and concat it at the very end when you return it, would be better.  At any rate, flesh it out, and you have an idea how to approach the rest of these. Fair warning, there could be problems but with this, it's all off the top of my head, but at least it should give you an idea how you should start approaching the process of coding these.

 

 

 

 

That's  what im talking about gizmola. what you just did above  in the quote section and how u just wrote that function even tho it was just of the top of your head and you are not sure it works That's what my problem is when i  start the coding process. i get stuck  i don't know if i should use the if, switch, or foreach statements like you did. how did u decide what statements to use? what process do take to know what  kind of statements ur going to to be using when u begin the code or function?

[gizmola]

It's just something you pick up over time, and get a feel for which types of loops to use.  Here, you have 3 different options that control the way the string is padded, so building that around a switch statement for each case tends to keep the code simple and clear. The same thing could be done with a big if-then-elseif statement.

 

For loops are good when you know exactly how many times you need to run through something.  While is good for when you need to loop until a condition is met (like fetching some unknown number of rows from a sql result set.)

 

Try not to get caught up in being overly concerned that you're "doing it wrong."  The worst thing that happens is you write bad code, and even writing bad code is going to teach you a lot. 

[loudog]

That is the hardest thing about all this, i am still not very familiar with loops and functions. so what is the  best way to learn how to use them and when to use them?? btw that last comment u made gizmola  really took some weight off me. I was trying to feel like  i was biting more than i could chew and was going to choke to death .thanks bro  for reminding me that this is learning process.

[Philip]

Try not to get caught up in being overly concerned that you're "doing it wrong."  The worst thing that happens is you write bad code, and even writing bad code is going to teach you a lot.

I'll definitely second that - you learn from your mistakes. I still do, and I've been doing this for many years... just when you get to dealing high-end sites make sure to not make those mistakes on a large live site / database (e.g. deleting all the members.) And if you do... and you don't learn from those kind of mistakes, you shouldn't be playing around with code

 

The PHP manual actually has pretty good explanations on each type of "control structure", with examples you can try. Like learning from your mistakes, learn by trying!