PHP basic syntax and data type learn notes

PHP basic syntax and data type:

(1), PHP basic syntax:

1, htm and PHP mixed
2, a statement to; (semicolon ends)
3, how to define a variable, and the use of variables

(2), PHP data operation type

Four scalar types:
Boolean (Booleans) understood as true or false
Integer (integral type)
Float (floating-point type, also "double") is interpreted as a decimal type
String (strings)

Two types of composite:
Array (arrays)
Object (Objects)

(3) PHP Five types of operations

1. Arithmetic operation

2, assignment operations (such as: $a =100)

3, Comparison operations (such as: $a < $b)

4, logical operation (such as: $a && $b)

5, incremental condensation operation (such as: $a + +)

(4) Switch conditional statement

Switch Conditional statement

<?php

$i = 1;

Switch ($i) {
Case 0;
The value of echo "I" is 0″;
Break
Case 1;
The value of echo "I" is 1″;
Break
Case 2;
The value of echo "I" is 2″;
Break
Default:echo "The above several values are not";

}

?>

Break n Jump Loop statement

Break n jump out of n-tier loops

Cases:

<?php
For ($i =1 $i <=5; $i + +) {
echo "i=". $i. " <br> ";
For ($j =1 $j <=5; $j + +) {
echo "&nbsp;&nbsp;j=". $j. " <br> ";
For ($k =1 $k <=5; $k + +) {
echo "&nbsp;&nbsp;&nbsp;&nbsp;k=". $k. " <br> ";
if ($k ==2) {
Break
}
}
if ($j ==3) {
Break 2;
}

}
echo "<br>";
}
?>

(5) Do While loop

<?php

Do a second judgment first.
do{
echo "Execution loop";
$a + +;
}while ($a >100);/note here's a semicolon.
echo "<br>";

To judge and execute first.
while ($a >100) {
echo "Execution loop";
$a + +;
}
?>

Functions that are commonly used in PHP arrays

foreach ($arr as $key => $val) {}//traversal array

Count ($arr)//counts the length of an array

Is_array ($arr)//array of Judgments

Explode ("key", $STR)//split string array