After using it for so long, the basic symbols of PHP were not fully recognized. I found the @ number and found it for a long time. post the basic symbol list. For more information, see ~ Annotation symbol:
// Single line annotation /**/Multi-line annotation |
Use of quotation marks
''Single quotes, no meaning, can be taken without any processing; "" Double quotes, php dynamic processing and output, usually used for variables. |
Variable form:
True is True; The other is False. |
Common variables:
String (numbers, Chinese characters, etc) Integer (1, 2, 3, 4, 5, 0,-1,-2, and so on) Double floating point number (decimal point) Array Object |
Available methods include gettype ($ mix) and settype ($ mix, $ typename );
Common symbols
\ "Double quotation marks \ Backslash \ N line feed \ R output \ T hop (TAB) |
Operator Number
+ Addition operation-subtraction operation * Multiplication/Division % Get remainder + + accumulate -- Accumulate 1. add strings |
Set operation
= Place the value on the right to the left (Yes) + = Add the right value to the left -= Reduce the value on the right to the left * = Multiply the value on the left by the value on the right. /= Divide the value on the left by the value on the right . = Add the string on the right to the left |
Bitwise operator
& | Or ^ Exclusive (xor) <Shift left > Shift to the right ~ 1 Population |
Logical operation
<Less> greater <= Less than or equal to> = greater than or equal ! = Not equal to & and | Or! No |
Other operators
$ Variable symbol & Variable indicators (before the variable) @ Do not display the error message (before the function) -> Object methods or attributes => Array element value ? : Ternary operator |
Basic method
1. PHP converts strings to uppercase and lowercase!
Strtolower (); converts characters to lowercase letters Strtoupper (); converts uppercase letters |
2. PHP encrypted string (case sensitive)
Md5 (); encryption Sha1 (); encryption |
3. quotation marks
I. single quotes are output as is
2. double quotation marks are output based on content interpretation
3. a single quotation mark is used to execute a command, such as 'pwd '.
4. "" acts on translated characters. for example, "" is a line break!
4. function: htmlspecialchars ()
This function converts special characters into HTML strings (&....;). The most common use case may be the message board for handling customer messages.
& (And) & "(Double quotation marks)" <(Less than) to < > (Greater than) to> |
This function only converts the preceding special characters and does not convert all of them into the ASCII conversion defined in HTML.
5. batch output HTML content!
Echo <EOT HTML output content... // Comments are output here! EOT;
Print < HTML output content... // Comments are output here! EOT; |
(Note: "{variable}" is used for internal variables }")
6. determine whether the file exists and the output content
$ FileName = "File. TXT "; If (File_Exists ($ FileName )){ Echo" ". File_Get_Contents ($ FileName )." "; } Else { Echo "no "; } ?> |
7. unset the variable;
Unset ($ var ); Unset ($ var, $ var1 ); |
8. is_int;
Checks whether the variable is an integer;
9. is_null;
Checks whether the variable is NULL;
10. is_string
Checks whether the variable is a string.
11. is_real;
Is_float () alias
12. isset
Check whether the variable is set
13. is_bool
Check whether the variable is Boolean
14. is_array
Checks whether the variable is an array.
15. is_object
Checks 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 "); |
Convert the escape line into HTML