- PHP code is enclosed by <?php and ?>
- It is mandatory to end every statement with a semicolon (;). Though semicolon for last statement (the statement just before ?> ) is not mandatory.
- The default file extension for PHP files is ".php".
- A PHP file normally contains HTML tags, and some PHP scripting code.
- All classes, keywords and user-defined functions are case- insensitive.
- Single line comment can be written as:
- Multi line comment can be written as:
// This is PHP code.
In the above example only the first statement will display the value of the $language variable, this is because $language and $LANGUAGE are treated as two different variables.
c language features
- Simple and Easy to learn.
- Powerful and Efficient.
application of c language
C language is used to develop a simple program and as well as complex Application and System software also. Some of the applications of C language are given below:
- Operating system
- Modern Programs
- Compiler, Assembler and Interpreter
- Network Drivers
- Text Editors and Print Spoolers.
Overview of Compiler and Interpreters
Before talking about the Compiler and Interpreter we have to know some important points as given below:
- A program is a set of instructions used to perform a particular task.
- These programs are written in assembly language or high level language (English words),this written program is called as source program which cannot be understood by the computer. Computer can only understand the instructions available in the form of machine language as '0' and '1'.
- The source program is to be converted to the machine language that is known as object program.
- Source program is converted into object program with the help of interpreter or compiler which are explained here in detail:
- Compiler reads the entire source program and converts it into the object program.
- Compiler provides errors of entire program at once instead of providing them line by line. Only error free program can be executed.
- Compiler consumes less time for converting source program to object program.
- Compiler is preferred where length of the source program is very large.
- Interpreter reads only one line of source program at a time and converts it into the object code.
- Interpreter provides error line by line.
- Interpreter consumes more time for converting source program to object program than compiler.