C header files and their functions is another important topic in C online tutorials. Here, you will know about header files in C language. Moreover, C header files and their uses is simple. However, you must practise header files in C example exercises. This way you will know C header files list as well. In addition, you will know include syntax, operation etc in header files.
What are header files in C language?
Header file in C programming is file with ‘.h’ extension. Moreover, this file has C function declarations. Even you can share macro definitions with other source files.
Furthermore, there are two different header files. One is files which programmer writes. While other are files which you get from computer.
Steps to use header file in C program
You may even use header file in C program. For this you must include C pre-processing directive ‘#include’. This is similar to C compiler’s header.
Steps to include syntax in C program
As we told you pre-processor includes system and user header files. Moreover, it uses directive ‘#include’. But it has two forms.
Form 1:to include syntax
#include <file> |
You will use this form for system header files. This looks for ‘file’ in standard list of system directories. Furthermore, you may add directories before to list. For this you should use –I option. You must remember to do this when you compile source code.
Form 2: to include syntax
#include “file” |
You use this form for header files. It looks for ‘file’ in directory. This directory has current file. Moreover, you can attach directories before list. But for this you must use –I option. This happens when compiling source code.
Steps to include operation in a C program
You must use ‘#include’ directive. Because this directs C pre-processor. In addition, you may scan specific file as input. To know more continue reading. We gave example program for your understanding. You may also read C operators to know better.
Example program
Once only headers in C language
Compiler processes contents twice. This case happens when you include header file twice. As a resultthere will be an error. However, you may prevent this. For this you must enclose real contents of file. Remember to do it in condition.
Example program
Note:
Whenever header is inclusive.Conditional turns to be false.Because here, you defined HEADER_FILE.Hence, pre-processor skips contents of file. Thus, compiler does not see it twice.
Computed includes
Conditions are helpful in programs. In addition, it will be advantage. Because this will select only one of different header files.You will include these files in program. You can check example program to understand it.
Program example
Computed include means that pre-processor uses macro for header name. Therefore, with ‘#include’ you may write header name. Finally this will be macro name.
Henceyou now know header files in C with their uses. But do not forget to practise C header files with functions examples. This chapter will help you with Type casting in C.
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