PHP common symbols and functions you must know to play

 

Variable shape:   one is true;   The other is false or false   common variable form:   string string (digit \ Kanji \ etc.)   integer integer (1, 2, 3, 4, 5, 0,-1,-2, etc.)   double floating-point number (small points)   Array   Object   available methods are GetType ($mix) and Settype ($mix, $typename);       Common symbols   \ "Double quotes   \ backslash"   \ line break   \ r send out   T-hop (TAB)   operation symbol   + addition shipping Count – Subtraction   * Multiplication Operations/Division operations  % take remainder + + cumulative  – 1. Add strings   Set operations   = Turn the value on the right to the left (must)   + = Add the right value to the left  -= to reduce the value on the right to the left of   *= the left value by the right  /= the value to the left by dividing the right   = Add the right string to the left   bitwise operation   & and   or   ^ Mutex (XOR)   << left shift   >> right Shift &nbsp ; ~ Take 1 of the complement   logic operation   < less than > greater than   <= is less than or equal to >= greater than or equal to  != not equal to && and   or! No   other operational symbols   $ variable symbol   & variable index (added to variable)   @ does not display error message (added to function)  -> object's method or property   => array element value  ? : Ternary operator   Basic method   1.PHP conversion string is case-insensitive!   Strtolower (); Turn characters to lowercase strtoupper (); Capitalize   2.PHP encrypted strings (uppercase and lowercase)   MD5 (); encrypt SHA1 (); About quotes   One, single quotes are the same as output two, double quotation marks are the contents of the interpretation of the output three, inverted single quotes 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 a special character to an HTML string format (&....;). The most commonly used occasions may be to deal with the message version of the customer message.   & (and) Turn to & "(double quotes) into" < (less than) into < > (greater than) into >   This function converts only the special characters above, and does not convert all to the ASCII conversion as defined in HTML 。   5. Bulk Output HTML content!   echo <<< EOT HTML output ... Here the annotation still output! EOT;   Print <<<eot HTML output ... Here the annotation still output! EOT; (Note: Internal contains variables with "{variable}")   6. Determine if the file exists and output   <?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 detect whether the variable is a string 11.is_real; Is_float () Alias 12.isset detects whether the variable is set 13.is_bool whether the variable is a Boolean 14.is_array detect whether the variable is an array 15.is_object detect whether the variable is an object 16.SubStr. SUBSTR (String,start,selectnum) echosubstr (' 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/>