PHP Note 01

PHP Output statements

(1) echo "helloworld! ";---echo command
(2) print (); The output statement is a function that has a return value. The output returned successfully to 1, and the failure returned 0.
(3) printf (); Format the output string. Example: printf ("%d,%f", 12,12.3);
(4) sprintf (); Format the stitching string, not the output statement, but only the string concatenation.
(5) Print_r (); Output arrays, objects, and other composite data types

1. Implicit conversions

$a = 1;

$b = 1.22;

$a = $b;

2. Casting

　

GetType ($ variable);

Settype ($ variable, "type")

Intval ($a)//$a data type unchanged, intval ($a) whole becomes shaping, zero conversion

Isset ()//variable exists

Unset ()//Destroy variable

Empty

function: Check if a variable is empty
* Return value:
* Returns TRUE if the variable does not exist
* If the variable exists and its value is "", 0, "0", NULL, FALSE, Array (), Var $var; and objects that do not have any properties, the TURE is returned.
* If the variable exists and the value is not "", 0, "0", NULL, FALSE, Array (), Var $var; And an object that does not have any properties, it returns FALSE

Judging variable types

Is_array (variable); Determine if the variable is an array, the following usage is the same

Array,double,float,real,long,int,integer,string,object,resourse,null,numeric

PHP Note 01