Abandoned fish--how long does PHP take to get from getting started to giving up? 3

today's Course: PHP 3- Day Foundation Consolidation video Tutorial "Yan 18"

variable Type: String, Integer, floating-point number, resource, array, object, NULL, Array

Null type // No value and no type

<?php

$a = null;

?>

detects if a variable exists //isset detection variable, returns false for the null type

if (Isset ($b)) {

echo ' variable b exists ';

}else{

echo ' variable b does not exist ';

}

get the variable type //gettype function

$b = ' 1 ';

Echo GetType ($b);

determine if the type you want is //is_int,is_float,is_array ...

Is_int,is_float,is_array

if (Is_int ($a)) {

echo "A is shaping ";

}else{

echo "A is not cosmetic ";

}

print variable //echo string , Print_r array,var_dump The type of the variable and its value

echo string , Print_r array,var_dump type and value of the print variable

$c = 1;

$d = Array (+/-);

Echo $c;

Print_r ($d);

Var_dump ($d);

Type conversions

$a = 1;

$a = $a. ' Hello ';

echo $a;

to the Boolean type of judgment, the value is considered a Boolean false, while the other refers to the original true:',' 0 ',0,0.0,false, NULL,Array ();

if (' = = False ') {

Echo ' empty string is false ';

}

?>

Assign value

value Assignment,

$a = 9;

$w = 10;

$w = $a;

Var_dump ($a, $w);//29.29

$w = ' W ';

Var_dump ($a, $w);//29.W

Reference Assignment

$a = 9;

$w = 10;

$w = & $a;

Var_dump ($a, $w);//29.29

$w = ' W ';

Var_dump ($a, $w);//w.w

destroy variable // destroyed variable value is NULL

destroyed

$a = 9;

unset ($a);

if (Isset ($a)) {

echo ' variable a exists ';

}else{

echo ' variable a does not exist ';

}

Dynamic Variable Name

Dynamic Variable name

$a = ' Hebei ';

$d = ' a ';

$e = ' d ';

Echo $a, $ $d, $$ $e;

Arithmetic operators

echo ' <br/> ';

$a = 10;

$b = 1;

echo $a/$b;// divisor cannot be 0

echo ' <br/> ';

$a = -10;//10,-10

$b = -3;//3,-3

echo $a% $b;//modulo algorithm, the result is positive or negative depending on the divisor

Tired Today, sleep.

The third day, did not give up, it seems really need to go heart ~ ~ ~

This article from "A Big big waste fish" blog, declined reprint!

Abandoned fish--how long does PHP take to get from getting started to giving up? 3