Basic symbols and usage in PHP _php base

Callout symbol:

single-line annotation /*/multi-line annotation

Use of Quotes

' single quotes, without any sense, without any processing directly brought over; "" Double quotes, PHP dynamic processing and then output, generally used for variables.

Variable form:

One is true; The other one is false or false.

Common variable form:

string strings (digital \ Kanji \ etc.) Integer integers (1, 2, 3, 4, 5, 0,-1,-2, etc.) Double floating-point number (decimal point) Array arrays Object objects

The methods available are GetType ($mix) and Settype ($mix, $typename);

Common symbols

\ "Double Quotes \ reverse Slash \ n Line Change \ r send out \ t Hop bit (TAB)

Operational symbols

+ addition operation-subtraction operation * Multiplication Operations/Division operations % take remainder + + additive --minus 1. Add strings

Set operation

= Put the value on the right to the left (must be) + = Add the right value to the left -= reduce the value on the right to the left *= multiply the value on the left to the right. /= divide the value on the left to the right. . = Add the right string to the left

Bit-Clerk operation

& and | Or ^ Mutual exclusion (XOR) << left Shift >> Shift Right ~ Take 1 of the complement

Logical operations

< less than > greater than <= is less than or equal to >= greater than or equal != not equal to && and || Or! No

Other operational symbols

$ variable Symbol Index of & variables (added to the variable before) @ Do not display error message (added to function) Methods or properties of the-> object The element value of the => array ? : Ternary operator

Basic methods

1.PHP conversion string is case-insensitive!

Strtolower (); Turn characters to lowercase Strtoupper (); Capitalize the character

2.PHP Encrypted string (case-insensitive)

MD5 (); encrypt SHA1 (); encrypt

3. About Quotes

One, single quotation mark is the original output

Two, double quotes are content interpretation for output

Three, reverse single quotation marks is to execute a command, such as ' pwd '.

Four, "\" role in the translation of characters, such as "\ n" for line-wrapping!

4. Function: Htmlspecialchars ()

This function converts special characters into an HTML string format (&....;). The most commonly used occasions may be to deal with the message version of the customer message.

& (and) Convert to & "(double quotes) into" < (less than) turn into < > (greater than) convert to >

This function converts only the special characters above, and does not convert all to the ASCII conversion specified by HTML.

5. Bulk Output HTML content!

Echo <<< EOT HTML Output content ... Here the annotation still output! EOT; Print <<<eot HTML Output content ... Here the annotation still output! EOT;

(Note: Internal contains variables with "{variable}")

6. Determine if the file exists and output content

<?php $FileName = "File.TXT"; if (file_exists ($FileName)) { Echo "<xmp>". File_get_contents ($FileName). " </xmp> "; }else { Echo "No"; } ?>

7. Unload variable unset;

Unset ($var); Unset ($var, $var 1);

8.is_int;

Detects whether a variable is an integer;

9.is_null;

Detects whether the variable is NULL;

10.is_string

Detects whether a variable is a string

11.is_real;

Alias for Is_float ()

12.isset

Detect whether a variable is set

13.is_bool

Detect whether a variable is a Boolean

14.is_array

Detects whether a variable is an array

15.is_object

Detects whether a variable is an object

16.SubStr.

SUBSTR (String,start,selectnum) echo substr (' abcdef ', 1); Bcdef echo substr (' abcdef ', 1, 3); Bcd echo substr (' abcdef ', 0, 4); Abcd echo substr (' abcdef ', 0, 8); ABCdef echo substr (' abcdef ',-1, 1); F

17.nb2br

echo nl2br ("foo isn ' t\n bar");

Turn the escaped newline into an HTML <br/>