problem with header file

while trying to run a program why it says couldn't define include file IOSTREAM???

 

iostream is a declaration for c++ programs
if you are using ccompiler it will not run
because c++ programs will not run in c compiler

or suppose your program is not running in c++ compiler(eg:-turbo) if we consider
go for 1) options menu
select compiler|c++ options
in the dialog box that appears select cpp always
now
you can run the program without errors