50th Day class PHP basic syntax

(01) PHP tagged <?php?>

<? ?>

<%%>

<script lauguage= "PHP" ></scrit>

(02) Output statement echo "", "", ""//Can output multiple

Print ""//Output only one

(03) Comments///* *

(04) data type int double float string char datetime (TIME) bool

(05) Define the variable $x = ""; Variable must start with $

(06) variable variable $a = "B";

$b = "word";

echo $ $a; The output is Word

(07) Determine if the variable has a value isset ()//null or 0 is false

(08) Clear variable unset ()

(09) Determine if the variable is empty ()

(10) Take the address character &

$a = 5;

$b =& $a;

$b = 10;

echo $a; Output is 10

(11) Output variable information details dump ()

Type name GetType ()

(12) Type conversion cast setType (variable, type)//cast variable to desired type

Type +var ()

(type) + variables such as (int) $a; Turn A into an integral type

Auto-conversion (rule) priority from high to low is floating point > Integer > Boolean, String

Boolean and string are converted to numeric types when the operation

string conversion to a number type only extracts the beginning of the number, E is 10 as the bottom of the multi-square

(13) stitching strings.         such as echo "". $a. ""; The middle of the output is a sentence of variable a

(14) Error suppressor @//Mask off error

(15) Conditional operator? : Structure: Judging condition? Output when correct: error when output

(16) escape character \ n line break \ r enter \ t Horizontal tabulation

(17) The variable echo "hello{$a}hi" can be parsed in double quotes

(18) Delimiter definition character channeling $a =<<

50th Day class PHP basic syntax