jayviannay / php-syntax-cheat

PHP Syntax Cheat beginner

Usefull natives functions

• isset() test for variable exists
• empty() test for empty variable
• var_dump($var) DEBUG : displays the information of a variable
• header() send a header from the server (redirect to)
• is_numeric() test to see if a value is a number
• exit() causes script top stop immediately
• str_replace('a','b', $string) replace a with b in a string
• trim($string) trims leading and trainling spaces
• explode($separator, $string) makes array of strings, each of which is a substring of the string parameter extracted using the separator
• implode($separator, $string) makes the elements of an array into a string
• count($array) count all elements from an array, or something in an object
• echo $string displays a string
• print_r($array) displays readable information for a variable
• require 'file.php' The include statement will issue E_ERROR if it cannot find the file, E_ERROR stops the script
• include 'file.php' The include statement will issue E_WARNING if it cannot find the file, E_WARNING doesn't stop the script

Control structure

| if syntax

if (/*condition(s) here */) {
    // code here
}

=> or

if (/*condition(s) here */) {
    // code here
} else {
    // other code here
}

=> or

if (/*condition(s) here */) {
    // code here
} elseif (/*condition(s) here */) {
    // other code here
} else {
    // other code here
}

| Switch syntax

Can be used with numbers, or strings

switch ($age) {
    case $age < 15:
        echo $age;
        break;
    case $age >= 15 && $age <= 25:
        echo $age;
        break;
    case $age >= 26 && $age <= 30:
        echo $age;
        break;
    default:
        echo "Well done";
}

Functions

| Simple function

function functionName()
{
    // here code 
    return $result;
}

| Function with parameter(s)

function functionName($param1, $param2)
{
    // here code uses param1 & param2
    return $result;
}

• Call function : functionName();
• Call & print result of a function : echo functionName();

Loops

| FOR (loop until a condition is met)

for($i = 0; $i < 5; $i++){
    echo $i;
}

output =>
0
1
2
3
4

FOREACH (loop through an array)

$array = ['Paris','c\'est','Gotham'];
foreach ($array as $value) { 
    echo $value;
}

output =>
Paris
c'est
Gotham

WHILE (loop through query results)

$i = 0;
do {
    echo $i++;
} while ($i < 5)

output =>
0
1
2
3
4

Arrays

• Create array : $myArray = array(); or $myArray = [];
• Push into array : $myArray[] = "​Som​eth​ing​";
• Push to associ​ative array : $myArr​ay[​'key'] = "​Val​ue";
• Create numeric array : $myArray = ['va​lue', 'value2'];
• Create associative array : $myArray = ['ke​y1'=​>'v​al1', 'ke​y2'=​>'v​al2'];
• Print from numeric array : echo $myArray[0];
• Print from associative array : echo $myArray['key'];
• Print array : print_r($myArray);
• Tips :
  • For associative array, keys are strings (example : 'firstname', 'lastname', 'email',...)
  • For numeric array, keys are numbers (Always 0, 1, 2...)

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