This article is forwarded from: blog.csdn.net/KH_FC/artic…

The following eight types of PHP data types are supported:

$a = true; $b = false; \\ Sets the value of variable b to falseCopy the code

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[** example 2**] PHP <? php $a = true; $b = false; If ($a == $b) {echo "; }else{echo "value not equal "; # false output}? >Copy the code

The output is as follows: Values are not equal [Example 3] Returns a Boolean value using an operator

      
	$name = "Zhang";
	if ($name= ="Zhang") {echo "His name is$name";	Print if the result is true
	}
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The output is as follows: His name is Zhang SAN

      
	if ($a = true ){
		var_dump($a);
	}
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Bool (true); bool(true); var_dump(); bool(true);

      
	if ($a) {
		var_dump($a);
	}
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$a = $a; $a = $a

1.2 the integer

Integer values contain only integers, which can also be used in octal, hexadecimal, and binary tables. Negative values can be preceded by optional – and + symbols. An octal integer that must be preceded by a 0 before being represented

      
	$a = 0456;
	var_dump($a);
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The output is: int(302), octal 456 converted to decimal is 302 [example 2] a hexadecimal integer that needs to be preceded by 0x

      
	$a = 0x456;
	var_dump($a);
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The output is as follows: int(1110), the hexadecimal 456 is 1110 when converted to decimal. [Example 3] The binary integer must be preceded by 0b

      
	$a = 0b1101;
	var_dump($a);
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The output is: int(13), the binary number 1101 is converted to decimal number 13 [Example 4] Print negative numbers, just add – before the positive number

      
	$a = -100;
	var_dump($a);
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Int (-100)

Generally, the maximum value of an integer is 2 billion characters, that is, 32 characters. The maximum value of an integer is 9E18 on a 64-bit platform. To check the maximum value and minimum value, run the PHP_INT_MAX and PHP_INT_MIN command

      
	var_dump(PHP_INT_MAX);
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Int (9223372036854775807); int(9223372036854775807)

      
	var_dump(PHP_INT_MIN);
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Int (-9223372036854775808) int(-9223372036854775808) int(-9223372036854775808)

      
	$a = 01239;
	var_dump($a);
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The following error message is displayed: 【Pay attention toAn integer value outside the integer range is interpreted as a floating-point number, as is the result of an operation outside the integer range. 【The sampleThe result of the operation is outside the integer range

      
	$num1 = 45678901111;
	$num2 = 89099899111;
	var_dump($num1 * $num2);
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Float (4.0699854804914E+21)

1.3 floating-point

Floating-point integers are also called real numbers. They can be expressed in both normal and technical format

      
	$a = 1.234;
	var_dump($a);
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The output is float(1.234)

      
	$a = 1.2 e3;
	$b = 8E - 10;
	var_dump($a);
	var_dump($b);
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Float (1200) float(8.0E-10)

1.4 the string

A string is a series of characters, a character is a byte, defined by single quotes, double quotes, Heredoc syntax constructs, and Nowdoc syntax constructs.

1. Single quotes

If you want to output a single quote, you need to add the escape character \\ to the single quote. If you want to output a backslash at the end, you need to add the escape character \\ before the character. If you add the escape character \ or \\ before other characters, you will directly output the escape character. [Example 1] Normally output a single-line character string

      
$a = 'I'm a string';
var_dump($a);
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The output is as follows: string(21) “I am a string” [Example 2] Normally the output is a multi-line string

      
$a = 'I'm a multi-line string';
var_dump($a);
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The output is: tring(23) “I am a multi-line string” [Example 3] Displays single quotes in a string

      
$a = 'I like \'PHP\'';
var_dump($a);
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The output is as follows: string(12) “I like ‘PHP'” [Example 4] Print backslashes in a string, usually used for file paths

      
$a = 'D:\\php\index.php';
var_dump($a);
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String (16) “D:\ PHP \index.php” string(16) “D:\ PHP \index.php” string(16) “D:\ PHP \index.php

      
$a = 'Joe';
$b = 'my name is $a';
$c = "My name is$a";
var_dump($b);
var_dump($c);
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$a = $a; $b = $a; $c = $a; Double quotation marks use double quotation marks to define strings. The character type to be defined is “”. When using double quotation marks to define strings, variables in the string will be interpreted without displaying their names. Escape character list:

echo "\$";
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[** Example 2**] double quotes PHP <? PHP echo "My Name is \" li Ming \"; ? >Copy the code

<<< define a string. When using a prompt to define a string, define an identifier after the prompt, then define a new line that contains the string you want to display, and end with the identifier. Identifier definitions must follow PHP rules and must contain only case, numbers, and underscores, but cannot start with underscores.

      
	$str = <<;
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The output is: My name is “zhangsan” has been added to CSDN for a year. Defining a string using the Nowdoc syntax is similar to defining a string using Heredoc, except that identifiers are surrounded by single quotation marks. Variables in a string cannot be interpreted as characters.

      
$name = "Zhang";
$str= < < <'test'
	My name is $nameMy name is Zhang SAN test;echo $str;
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The command output is: My name is $name My name is zhangsan

2. Compound types

Compound types include both array and object data types

"Name" => "age" => "11",Copy the code

); var_dump($array); ? >

Output: ` ` ` array (2) {/ "name" = > string (6) "zhang SAN" (" age ") = > string (3) the "11"} ` ` ` 2 * * * * instance 】 【 direct assignment to create an array ` ` ` PHP <? $array = ["name" => "$array ", "age" => "11",]; var_dump($array); ? >Copy the code

Array (2) {[“name”]=> string(6) “age” [“age”]=> string(3) “11”

      
$array = array("Zhang"."Bill"."Fifty");
var_dump($array);
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The output is: Array (3) {[0]=> string(6) “three” [1]=> String (6) “four” [2]=> String (6) “five”} When the first one reads an array from zero, it can be read with the index name enclosed in square brackets

      
$array = array(
	"name"= >"Zhang"."age"= >"11",); var_dump($array['name']);
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The output is: string(6) “triple”.

      
$array = array(
	"name"= >"Zhang"."age"= >"11",);$array['name'] = "Bill";
var_dump($array);
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The output is: the array (2) {/ “name” = > string (6) “bill” (” age “) = > string (2) the “11”}

2.2 object

Objects are the basis of object-oriented programming, and are instantiated in PHP using new, that is, creating objects

      
class test{
	function fu(){
		echo "test"; }}$test = new test;
$test->fu();
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The command output is test

3. Special type

Special data types include resources and null values

Echo "variable null ";Copy the code

}else{echo “variable not empty “; }? >

The output is: the variable is not emptyCopy the code