What are the basic types of variables in php

In PHP, there are four basic types of variables: 1. String (string) type, which is a continuous sequence of characters; 2. Integer (integer) type; 3. Float (floating point) type; 4. Boolean type, with only two values: true and false.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

In PHP, data types can be divided into three The major categories are scalar data types, composite data types and special data types.

The scalar data type is the most basic unit of the data structure. It is a basic data type and can only store one piece of data. There are four types of scalar data types in PHP, as shown in the following table:

Type	Function
string (string)	A string is a continuous sequence of characters
integer (integer type)	Integer type contains all integers, It can be a positive number or a negative number
float (floating point type)	Floating point type is also used to represent numbers. Unlike integers, it can not only represent integers. It can also be used to represent decimals and exponents
boolean (Boolean)	The simplest data type, with only two values: true (true) / false ( False)

string (string)

A string is a continuous sequence of characters. In other languages, Characters and strings are two different data types, but in PHP, characters and strings are uniformly regarded as string data types. In PHP, there are three ways to define strings, namely single quotation mark method, double quotation mark method, and Heredoc method.

<?php
header("Content-type:text/html;charset=utf-8");
//双引号方式声明字符串
$str1 = "hello";
//单引号方式声明字符串
$str2 = &#39;欢迎来到PHP中文网&#39;;
//Heredoc 方式声明字符串
$str3 = <<<EOF
    url：
    https://www.php.cn/
EOF;
echo $str1 . "<br>" . $str2 . "<br>" . $str3;
?>

integer (integer)

In PHP, integer variables are called integer or int types, Used to represent an integer. The rules for integer types are as follows:

• The integer type must have at least one number (0 to 9);

• The integer type cannot contain commas or spaces;

• The integer type cannot contain a decimal point;

• The integer type can be a positive or negative number.

The value range of the integer type must be between -2E31 and 2E31, and can be expressed in three formats, namely decimal, hexadecimal (prefixed with 0x) and Octal (prefixed with 0).

<?php
header("Content-type:text/html;charset=utf-8");
$x = 5985;
// 定义一个整型数据类型的变量
var_dump($x);
// 输出此变量
$x = -345;
var_dump($x);
$x = 0x8C;
//十六进制数字
var_dump($x);
$x = 047;
//八进制数字
var_dump($x);
?>

Note that in the PHP7 version, strings containing hexadecimal characters are no longer treated as numbers, but as ordinary strings , for example:

float (floating point type)

The floating point type is called the float type in PHP, and can also be called real numbers, which can be used to store integers. And decimals, the valid value range is between 1.8E-308 and 1.8E 308. Floating point numbers have higher precision than integer data types.

The sample code is as follows:

<?php
header("Content-type:text/html;charset=utf-8");
$num1 = 10.365;
$num2 = 2.4e3;
$num3 = 8E-5;
var_dump($num1, $num2, $num3);
?>

boolean (Boolean type)

The Boolean type has only two values, They are TRUE and FALSE (not case sensitive), meaning logical true and logical false. The sample code is as follows:

<?php
header("Content-type:text/html;charset=utf-8");
$x = TRUE;
$y = faLsE;
var_dump($x, $y);
?>

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