[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Y] [Z] ! (exclamation point) != (inequality) operator !== (not identical) operator type specification modifier " (quotes, double) double-quoted strings escape sequences in variable interpolation in HTML entity for in heredocs in SQL queries in string literals # (hash marks) in comments $ (dollar sign) in regular expressions 2nd 3rd 4th in variable names 2nd $_COOKIE array $_FILES array accessing form parameters $_GET array 2nd accessing form parameters $_POST array accessing form parameters $_SERVER array HTTP request headers, entries for $db->query( ) method $GLOBALS array $HTTP_COOKIE_VARS array $HTTP_ENV_VARS array $HTTP_POST_FILES array $HTTP_POST_VARS array $HTTP_RAW_POST_DATA variable $HTTP_SERVER_VARS array $HTTP_SESSION_VARS array $PHP_SELF variable (current script name) % (percent sign) % (modulus) operator %= (modulus assignment) operator in format string to printf( ) & (ampersand) & (bitwise AND) operator &= (bitwise AND assignment) operator converting to HTML entity indicating passing by reference > (angle bracket, right) > (greater than) operator in string comparisons >> (right shift) operator >= (greater than or equal to) operator in string comparisons converting to HTML entity greater than operator < > (angle brackets) (inequality) operator as pattern delimiters < (angle bracket, left) < (less than) operator in string comparisons << (left shift) operator <<< (heredoc identifier) <= (less than or equal to) operator in string comparisons converting to HTML entity <?php ?> tags (for PHP code) <br /> tag, inserting before all newline characters <script> tags, enclosing PHP code in ' (quotes, single) HTML entity for in heredocs in SQL queries in string literals escape sequences in single-quoted strings ( ) (parentheses) as pattern delimiters grouping operands for precedence grouping patterns in regular expressions non-capturing groups (float) casting operator (int) casting operator (object) casting operator (string) casting operator * (asterisk) * (multiplication) operator *= (multiplication assignment) operator in greedy and non-greedy quantifiers + (plus sign) + (addition) operator + (arithmetic assertion) operator ++ (autoincrement) operator += (addition assignment) operator in greedy and non-greedy quantifiers printing positive numbers with spaces, encoding in URLs 2nd , (comma) ASCII value for two or more, skipping array values in list( ) - (hyphen) -> construct, accessing properties and methods 2nd defining character range in regular expressions inline pattern matching options, turning off - (minus sign) - (arithmetic negation) operator - (subtraction) operator -- (autodecrement) operator -= (subtraction assignment) operator for right-justified strings . (dot) . (string concatenation) operator .+ (concatenation assignment) operator in cookie names, decoding in HTML field names, converting for PHP variables single-character matches in regular expressions wildcard match character / (slash) / (division) operator /* */, in multiline C-style comments //, in C++-style comments /= (division assignment) operator type specification modifier ; (semicolon) after terminating heredoc identifier before PHP closing tag in PHP statements = (equal sign) => symbol, separating array indexes from values = (equals sign) = (assignment) operator == (equal to) operator 2nd comparing strings with === (identity) operator comparing strings with testing return value for failure ? (question mark) ?\: (conditional) operator 2nd in non-greedy quantifiers placeholder in database queries replacing characters outside target encoding @ (at sign), error suppression operator [ ] (brackets) [[\:>\:]] end of word anchor in regular expressions as pattern delimiters in regular expression character classes [] (brackets), [[\:<\:]] start of word anchor in regular expressions \ (backslash) escaping in lookbehind pattern assertions in single-quoted strings regular expression metacharacters in SQL queries removing from escaped strings \: (colon), ending if line \A (beginning of string) anchor, Perl regular expressions \B (non-word boundary), Perl regular expressions \b (word boundary), Perl regular expressions \n (newlines) end of string matching in regular expressions in heredocs \Z and \z (end of string) anchors, Perl regular expressions ^ (caret) ^ (bitwise XOR) operator ^= (bitwise XOR assignment) operator negating regular expression character classes start of line anchor, Perl regular expressions start of string anchor in regular expressions 2nd _ (underscore) _ _ , method names beginning with converting dots (.) in cookie names to converting dots (.) in HTML field names to ` (backtick) operator security risks of { } (curly braces) {{{ and }}} sequences in comments as pattern delimiters enclosing array lookup in in code blocks 2nd variable interpolation in strings | (vertical bar) | (bitwise OR) operator |= (bitwise OR assignment) operator alternatives, in regular expressions type specification modifier ~ (tilde), bitwise negation operator 24-bit color |