Write well and work well - PHP basics (2)

　Hi

I haven’t written for a long time. When I wrote it yesterday, I feel like someone still read it, at least one or two comments~~ Good job!

There are only 4 things that you need to stick to every day: write this, learn a little French, read for a while, and exercise. There are benefits to being single.

1. PHP

1. Basics of PHP (2)

1.3 Data types

8 types - 4 types of scalars: boolean, integer, float/double, string; 2 types Composite: array, object; 2 special types: resource, NULL;

It is recommended to remember English. In the process of learning, variables are usually named this way.

php is a weakly typed language, that is, there is no need to declare the type of variables in advance.

Check the type of variable: gettype();

Judge the type: is_*(), where * is the abbreviation of various data types.

1.3.1 Boolean

true or false, not case sensitive, it is customary (for me) to write all lowercase.

Generally there is no need to cast to Boolean value, the system automatically determines; (see the example below)

These are considered false: false; 0; 0.0; empty string and string "0"; empty array; NULL; SimpleXML object generated from empty tags (I don’t understand it very well, mainly because XML is not involved yet);

Correspondingly, everything else considers it to be true - note that -1 is also true;

$boola=true;
$boolb=false;
$boolc=null;
$boold=-1;
$boole="sdkljf";

echo gettype($boola)."

---

";

function isbool($bool){
if(is_bool($bool)){
echo "You are damn right.It is boolean."."
";
}else{
echo "Sorry, it is not this type. Please try again."."
";
}
}

isbool($boola);
isbool($boolc);
isbool($boold);
isbool($boole);

function booluse($bool){
if($bool){
echo "It is equal to TRUE."."
";
}else{
echo " It is equal to FALSE."."
";
}
}

booluse($boola);
booluse($boolc);
booluse($boold);

Note in the above example , if you directly determine whether it is boolean, general data types will not be forced to convert. Only when used in if and other judgments will they be automatically and forcibly converted to boolean for use.

1.3.2 Int

Integer type.

I was wrong. . . Halfway through writing, my boss called me to work overtime, and I promise to finish the first part of the series tomorrow (I mean I want to watch Chinatown tonight...).

Good night, I went to read a book

The above has introduced the basics of writing well and doing well - PHP basics (2), including aspects of content. I hope it will be helpful to friends who are interested in PHP tutorials.