What are the scalar data types in php

There are four types of scalar data types in php: 1. boolean (Boolean), which has only two values: true and false; 2. string (string), which is a continuous sequence of strings, consisting of numbers. , composed of letters and symbols; 3. integer (integer type); 4. float (floating point type).

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

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

Among them, the scalar data type is the most basic unit of the data structure 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
boolean (Boolean)	The simplest data type, only two values: true (true) / false (false)
string (string)	String is a continuous sequence of characters
integer (integer type)	Integer type contains all integers, which can be positive or negative numbers
float (floating point type)	Floating point type is also used to represent numbers. Unlike integer type, in addition to integers, it can also be used to represent decimals. and index

1. Boolean

The Boolean type is one of the more commonly used data types in PHP. Save a true value or false value, where true and false are internal keywords of PHP. To set a Boolean variable, just assign true or false to the variable. In PHP, not only boolean values ​​are false, but non-boolean values ​​are also considered false in some special cases. For example, 0, empty string and just declare array without assignment.

2. String type (string)

A string is a continuous sequence of strings, consisting of numbers, letters and symbols. Each character in the string takes up only one byte. There are three ways to define strings, single quotes, double quotes, and delimiters (<<<)

Variables contained in backticks are output as ordinary characters, such as $ i='I'm the best', echo '$i' will output $i, and double quotes will parse the variable and output "I'm the best"!

The sample code is as follows:

<?php
    //双引号方式声明字符串
    $str1 = "PHP中文网";  
    //单引号方式声明字符串
    $str2 = &#39;PHP 教程&#39;;      
    //Heredoc 方式声明字符串
    $str3 = <<<EOF
    url：
    https://www.php.cn/
EOF;
    echo $str1."<br>".$str2."<br>".$str3;
?>

The running results are as follows:

PHP中文网
PHP 教程
url： https://www.php.cn/

3. Integer type (integer)

Integer data types can only contain integers.

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

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

• The integer type cannot contain commas or spaces;

• The integer type cannot contain a decimal point;

• Integers can be positive or negative numbers.

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
    $x = 5985;      // 定义一个整型数据类型的变量
    var_dump($x);   // 输出此变量
    echo "<br>";
    $x = -345;
    var_dump($x);   
    echo "<br>";
    $x = 0x8C;      //十六进制数字
    var_dump($x); 
    echo "<br>";
    $x = 047;       //八进制数字
    var_dump($x);
?>

Run the above code, the results are as follows:

int(5985)
int(-345)
int(140)
int(39)

4. Floating point type (float)

The floating point data type is both It can be used to store integers or decimals.

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

The sample code is as follows:

<?php
    $num1 = 10.365;
    $num2 = 2.4e3;
    $num3 = 8E-5;
    var_dump($num1, $num2, $num3);
?>

The running results are as follows:

float(10.365) float(2400) float(8.0E-5)

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