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Creating web pages in PHP

C++

Html

MySQL

Perl

Php

Shell


1. Array

2. File

3. Pattern matching

4. String


1. Array


1.1. Creating array


Simple array:


  $array = array("one", "two", "three");


Multidimensional array:


  $row_0 = array(1, 2, 3);

  $row_1 = array(4, 5, 6);

  $row_2 = array(7, 8, 9);

  $array = array($row_0, $row_1, $row_2);


Hash:


  $array = array(

                  "first" => "one",

                  "second" => "two",

                  "third" => "three"

                );


Hash with multiple values:


  $array = array(

                  "first" => array("one", "uno"),

                  "second" => array("two", "due"),

                  "third" => array("three", "tre")

                );


1.2. Adding value to array


Add at index 4:


  $array[4] = "four";


Add at the end of the array:


  $array[] = "end";


1.3. Accessing value in array


Simple array:


  $value = $array[0];


Multidimensional array:


  $value = $array[$row][$colomn];


Hash:


  $value = $array["second"];


Hash with multiple values:


  $row = $array["second"];


  $value = $array["second"][$language];


Subset of values:


  $subset = array_slice($array, $offset, $length);


1.4. Walking through an array


Simple array:


  for($array as $value)

  {

    print "$value\n";

  }


or


  for($i = 0; $i < count($array); $i++)

  {

    print "$value[$i]\n";

  }


or


  echo $array;


Hash:


  foreach($array as $key => $value)

  {

    print "$key: $value\n";

  }


Note that if one of the elements is not into the array, there will be an error in the foreach loop.


Hash with multiple values:


  foreach($array as $key => $values)

  {

    foreach($values as $value)

    {

      print "$value\n";

    }

  }


Note that if one of the elements is not into the array, there will be an error in the foreach loop.


1.5. Getting length of an array


  count($array);


1.6. Checking if is an array


  if(is_array($x) == true)

  {

    echo "is an array";

  }

  else

  {

    echo "is not an array";

  }


1.7. Checking for key existence


  $key = "third";

  if(isset($array[$key]))

  {

    print "$key is present\n";

  }


1.8. Checking for value existence


Simple array:


  $value = "three";

  if(in_array($array, $value))

  {

    print "$value is present\n";

  }


1.9. Finding position of a value


  $value = "three";

  $position = array_search($array, $value);

  if($position != false)

  {

    print "$value is in position $position\n";

  }


1.10. Iterator functions


Returns element pointed at by the iterator:


  $current = current($array);


Moves iterator to first element and returns it:


  $first = reset($array);


Moves iterator to next elment and returns it:


  $next = next($array);


Moves iterator to previous element and returns it:


  $previous = prev($array);


Moves iterator to last elment and returns it:


  $last = end($array);


Returns key and value of the current element and moves iterator to next element:


  list($key, $value) = each($array);


Returns key of current element:


  $key = key($array);


1.11. Deleting element from array


One element:


  unset($array[3]);

  unset($array["third"]);


Multiple noncontiguos elements:


  unset($array[3], $array[5]);

  unset($array["third"], $array["fifth"]);


Multiple contiguous elements:


  array_splice($array, $offset, $length);


1.12. Splitting array


  list($first, $second, $third) = $array;


1.13. Appending array


  $array = array_merge($array1, $array2);


1.14. Sorting array


By values (alphabetically), then reassign indexes starting with 0:


  $numbers = array("one, "two", "three");


[0]: "one"

[1]: "two"

[2]: "three"


  sort($array);


[0]: "one"

[1]: "three"

[2]: "two"


Same as before, but sort numerically:


  sort($array, SORT_NUMERIC);


If the array is a hash:


By key:


  ksort($hash);


By key, reverse order:


  krsort($hash);


By key, with user defined function:


  function mySortFunction ($a, $b)

  {

    if($a == $b)

      return 0;

    return ($a > $b) ? -1 : 1;

  }


  uksort($hash, mySortFunction);


By values:


  asort($hash);


By values, reverse order:


  arsort($hash);


By values, with user defined function:


  function mySortFunction ($a, $b)

  {

    if($a == $b)

      return 0;

    return ($a > $b) ? -1 : 1;

  }


  uasort($hash);


1.15. Removing duplicate values from array


  $array_unique = array_unique($array);


1.16. Comparing arrays


Union:


  $union = array_unique(array_merge($array1, $array2));


Intersection:


  $intersection = array_intersection($array1, $array2);


Difference:


  $difference = array_diff($array1, $array2);


Symmetric difference:


  $symmetric_difference = array_merge(array_diff($array1, $array2), array_diff($array2, $array1));


2. File


2.1. Reading file line by line


  $file = 'myfile.txt';

  $fh = fopen($file, 'r') or die($php_errormsg);

  while(!feof($fh))

  {

    $line = rtrim(fgets($fh, 1048576));

  }

  fclose($fh) or die($php_errormsg);


3. Pattern matching


3.1. Replace


Replace all double blanks with &nbsp;&nbsp;


  $line = ereg_replace('  ', '&nbsp;&nbsp;', $line);


4. String


4.1. Controlling case


Convert to uppercase:


  $uppercase = strtoupper($string);


Convert to lowercase:


  $lowercase = strtolower($string);




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Last modified on 2024-08-02