1.PHP syntax environment
①: Standard form ( commonly used ) <?php here is the code ?>
②: Standard form <script language='php'> Here is the code</script>
③: Short tag form ( not recommended ) <? Here is the php code ?> Note: This form depends on a setting in php.ini: short_open_tag=on
④: The closing tag can sometimes be omitted:
When there is no other non-php code (usually html) behind the php code part of a php file, the last end tag of the php code area can be omitted at this time: Note: you cannot hit enter below echo, otherwise it will be output together
2. Syntax form:
①: Variable names are case-sensitive
②: Constants are also distinguished, generally all uppercase
③: The function name is not distinguished (how to write the call when it is defined)
④: System keywords do not distinguish such as: if, else, for