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This article mainly introduces how php transforms data types. It is very detailed and has a certain reference value. Friends who are interested must finish reading it!

Strong conversion method: 1, add the target type enclosed in parentheses before the variable to be converted ("(int)", "(bool)", "(float)", etc.); 2, use the type conversion function intval (), floatval (), boolval (), strval (), settype ().

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

PHP forced type conversion

Cast in PHP is similar to other languages in that you can precede the variable to be converted with the target type enclosed in parentheses (for example, $var = (int) 3.1415;), or you can use specific type conversion functions (such as intval (), floatval (), strval (), etc.) or settype () to convert the type.

When you cast a variable type by adding a target type enclosed in parentheses, the types of variables allowed in parentheses are as follows:

(int), (integer): convert to integer

(bool), (boolean): convert to Boolean type

(float), (double), (real): convert to floating point type

(string): convert to string type

(array): converting to an array type

(object): converts to an object type.

When you use specific conversion functions intval (), floatval (), boolval (), strval (), and so on to convert the types of variables, the functions of these functions are as follows:

Intval (): used to get the integer value of a variable

Floatval (): used to get the floating-point value of a variable

Boolval (): used to get the Boolean value of the variable

Strval (): used to get the string value of the variable.

[example] use the above functions to cast the type of a variable.

The running results are as follows:

The type of variable $int is: integer variable $float is of type: double variable $string is of type: string

Neither of the two cast methods described above changes the type of the converted variable itself, but by assigning the new type of data converted to the new variable, the type and value of the original variable remain unchanged.

If you need to change the type of the variable itself, you can use the settype () function, which has the following syntax format:

Settype (mixed & $var, string $type)

Where $var is the variable to be converted; $type is the type to be converted, which can be boolean (bool), integer (int), float (double), string, array, object, null.

[example] use the settype () function to cast the type of variable.

The running results are as follows:

The type of $str is: type of integer$bool is: string

There are the following points to note when using cast:

Integer type is converted to floating point type, and because the precision range of floating point type is much larger than that of integer type, the precision after conversion will not change.

When a floating-point type is converted to an integer, the fractional part is automatically discarded, leaving only the integer part. If a floating point number exceeds the valid range of an integer number, the result will be uncertain.

When a string is converted to a number, it starts from the string to the end of the first character that is not a number (the content that does not match is cleared), that is, if the first character of the string is not a number, the converted result is 0

The NULL value is converted to a string and the result is an empty character.

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