it would have been great if u could explain the basic syntax of build with example....
BUILD is a very function rich operand - it has a great number of parameters for doing different things.
A very basic
example would be:
to put input positions 1-10 and 21-40 in the output record.
But that's only one very simple use of BUILD out of many more simple and complex uses.
If you had asked for something specific, I would have given you a specific example matching what you asked for. But when you ask for something as general as "the example on how to use a build function" all I can give you is a pointer to the books.
Ask more specific questions if you want more specific answers.