Chubby Learn PHP summary 1-php data types

PHP supports a total of 8 primitive types, including 4 winning types, namely: Boolean (Boolean), Integer (Shape), float/double (floating point), and String (string), two composite types: Array (array) and object (objects) ; Two special types, namely: resource (Resource) and null.

1.1 Scalar data types

1.1.1 Boolean type

Typically, Boolean types are used in expressions that are applied to a condition or loop statement, and the following in the IF condition statement determines whether the value in the variable is true, and then outputs the respective information.

Note: In PHP, not only false values are false, in some special cases the Boolean value is also considered false, these special cases are: 0, 0.0, "0", a blank string (""), only declare an array with no assignment, and so on.

Description: The dollar sign $ is the identifier for the variable, and all variables begin with the $ character, whether declaring a variable or calling a variable, should use the $ symbol.

1.1.2 The String type (string)

In PHP, there are 3 ways to define strings, namely single quotation marks ('), double quotation marks ("), and delimiters (<<<).

 
  ";? >

If you need to use a swivel chair character, use single quotation marks to escape only single quotes "'", when using double quotation marks, there is a lot to be aware of escaping, usually using backslashes \ to escape.

1.1.3 Integer Integer

The integral type does not have to say more, look at the code:

 
  The result of "; echo" decimal is: $str 1
The result of "; echo" hexadecimal is: $str 2
The result of "echo" octal is: "; if ($str 3 = = $str 4) {    echo ' &str3=&str4= '. $str 3;} else{    echo ' $str 3! = &str4 ';}? >

1.1.4 floating Point type

Floating-point data types can be used to store numbers or to hold decimals, and in previous versions of PHP4.0, floating-point markers are double, also called double-precision floating-point numbers, but not both. Floating-point numbers have two writing formats, one of which is the standard format: 3.1415; and one is the scientific notation format: 3.58E1.

 
  '; Echo ' pi 3 in writing:
'; Echo ' the first type: pi () = '. Pi (). '
'; Echo ' the second type: 3.1415926 = '. 3.1415926. '
'; Echo ' third: 3145926E-11 = '. 314159265359E-11. '
';? >

Not to be continued ...

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