Annotation symbol:
| // Single line annotation /* */ Multi-line annotation |
Use of quotes
| ' ' Single quotes have no meaning and are taken directly without any treatment; " "Double quotes, php dynamically processed and then output, which is generally used for variables. |
Variable form:
| One is True, that is, true; The other is False, that is, false |
Common variable patterns:
| string string (number\Chinese characters\etc) integer integer (1, 2, 3, 4, 5, 0, -1, -2, etc.) double floating point (decimal point) array array object object |
The methods that can be used are gettype($mix) and settype($mix,$typename);
Common symbols
| \" Double quotes \\ Backslash \n Line break \r Send out \t Jump position (TAB) |
Operator symbols
| + Addition - Subtraction * Multiplication / division % Take the remainder ++ Accumulate -- Cumulative 1. Add strings |
Setting operation
| = Substitute the right value into the left (must know) += Add the right value to the left -= Subtract the value on the right to the left *= Multiply the left value by the right /= Divide the left value by the right .= Add the string on the right to the left |
Staff operation
| & and | or ^ Mutual Exclusion (xor) << Shift to the left >> Shift to the right ~ Take the complement of 1 |
Logical operations
| < Less than > Greater than <= Less than or equal >= Greater than or equal != does not equal && and || Or ! No |
Other operator symbols
| $ variable symbol & variable indicators (added before variables) @ No error message is displayed (added before function) -> Object method or property => Element values of array ? : Triple operator |
Basic Methods
Convert string to upper and lower case!
| strtolower(); convert characters to lowercase strtoupper(); convert characters to uppercase |
Encrypted strings (both upper and lower case)
| md5(); Encryption sha1(); Encryption |
3. About Quotes
1. Single quotes are output as is
2. Double quotes are the content interpretation for output
3. Anti-single quotes are to execute a command, such as `pwd`.
4. "\" acts on the translated characters, such as "\n" is a newline!
4. Function: htmlspecialchars()
This function converts special characters into HTML string format ( &...; ). The most commonly used occasion may be to process the message version of customer messages.
| & (and) convert to & " (Double Quotes) to " < (less than) to < > (greater than) to > |
This function only converts the special characters above and will not all convert into the ASCII conversion specified in HTML.
5. Batch output HTML content!
| echo <<< EOT HTML output content. . . //The comments here are still output! EOT; Print <<<EOT HTML output content. . . //The comments here are still output! EOT; |
(Note: Use "{variable}" to include internal variables)
6. Determine whether the file exists and output the content
| <?php $FileName=""; if (File_Exists($FileName)){ Echo "<xmp>".File_Get_Contents($FileName)."</xmp>"; }else { Echo"no"; } ?> |
7. Uninstall the variable unset;
| unset($var); unset($var,$var1); |
8.is_int;
Detect whether a variable is an integer;
9.is_null;
Detect whether the variable is NULL;
10.is_string
Detect whether a variable is a string
11.is_real;
is_float() alias
Detect whether the variable is set
13.is_bool
Detect whether the variable is boolean
14.is_array
Detect whether a variable is an array
15.is_object
Detect whether a variable is an object
.
| 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 escaped line breaks into HTML<BR />