Basic symbols in PHP and how to use them

Basic symbols in PHP and how to use them

Core tip: With so long, even PHP basic symbols are not recognized, see the @ is also checked for a long time to know what meaning. Put a list of basic symbols, you need a friend to refer to.

With so long, even PHP basic symbols are not recognized, see the @ is also checked for a long time to know what meaning. Put a list of basic symbols, you need friends can refer to ~

Annotation symbols:

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Single-line annotations /* * * Multi-line annotations

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Use of quotation marks

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' Single quotation marks, without any meaning, are brought directly over by any treatment; "" Double quotes, PHP dynamic processing then output, typically used for variables.

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Variable pattern:

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One is true, that is true; The other is false or false.

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Common variant Patterns:

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string strings (numeric \ Kanji \ etc) Integer integers (1, 2, 3, 4, 5, 0, 1, 2, and so on) Double floating point number (decimal point) Array arrays Object objects

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

Common symbols

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\ "Double quotation marks \ \ Backslash \ nthe line break \ r send out \ t-hop (TAB)

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Operation symbols

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+ addition operations-subtraction operations * Multiplication Operation/division operation % take remainder + + accumulate --minus 1. Add the strings together

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Set operation

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= 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 left value by the right. /= divide the left value to the right . = Add the right string to the left

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Bit operator

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

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Logical operations

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

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Other operational symbols

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$ variable Symbol Indicator of the & variable (before the variable) @ Do not display error message (added before function) The method or property of the object = = element value of array ? : Ternary operator

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Basic methods

1.PHP convert string to case!

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Strtolower (); Turn character to lowercase Strtoupper (); Turn characters into uppercase

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2.PHP Encrypted string (case-sensitive)

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MD5 (); encryption SHA1 (); encryption

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3. About quotation marks

One, single quotation marks are output as-is

Two, double quotation mark is the content explanation carries on the output

Third, anti-single quotation marks are the execution of a command, such as ' pwd '.

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

4. Function: Htmlspecialchars ()

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

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& (and) turn into & "(double quotation marks) to turn" < (less than) turn into < > (greater than) turn into >

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

5. Batch Output HTML content!

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Echo <<< EOT HTML Output content ... Here the comment output! EOT; Print << HTML Output content ... Here the comment output! EOT;

(Note: internal contains variable with "{variable}")

6. Determine if the file exists and output the content

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

7. Unload variable unset;

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

8.is_int;

Detects if the variable is an integer;

9.is_null;

Detects if the variable is NULL;

10.is_string

Detects if a variable is a string

11.is_real;

Alias for Is_float ()

12.isset

Detect if a variable is set

13.is_bool

Detects if a variable is a Boolean type

14.is_array

Detects if a variable is an array

15.is_object

Detects if a variable is an object

16.SubStr.

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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

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

To turn an escaped newline into HTML.

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