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What is a preprocessor in Computer Science?
How does a preprocessor work?
What is a C preprocessor?
What is a preprocessor file in C?
What happens when a file is included in a preprocessor?
How does a preprocessor change a code file?
In computer science, a preprocessor (or precompiler) [1] is a program that processes its input data to produce output that is used as input in another program. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers.
- Preprocessor Directives in C
- Types of C Preprocessors
- Macros
- File Inclusion
- Conditional Compilation
- Other Directives
- Frequently Asked Questions on C Preprocessors
Preprocessor programs provide preprocessor directives that tell the compiler to preprocess the source code before compiling. All of these preprocessor directives begin with a ‘#’ (hash) symbol. The ‘#’ symbol indicates that whatever statement starts with a ‘#’ will go to the preprocessor program to get executed. We can place these preprocessor dire...
There are 4 Main Types of Preprocessor Directives: 1. Macros 2. File Inclusion 3. Conditional Compilation 4. Other directives Let us now learn about each of these directives in detail.
In C, Macros are pieces of code in a program that is given some name. Whenever this name is encountered by the compiler, the compiler replaces the name with the actual piece of code. The ‘#define’directive is used to define a macro.
This type of preprocessor directive tells the compiler to include a file in the source code program. The #include preprocessor directiveis used to include the header files in the C program. There are two types of files that can be included by the user in the program:
Conditional Compilation in C directivesis a type of directive that helps to compile a specific portion of the program or to skip the compilation of some specific part of the program based on some conditions. There are the following preprocessor directives that are used to insert conditional code: 1. #if Directive 2. #ifdef Directive 3. #ifndef Dire...
Apart from the above directives, there are two more directives that are not commonly used. These are: 1. #undef Directive 2. #pragma Directive
Are Macros Stored in Memory like Functions?
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Feb 8, 2018 · A Preprocessor is a system software (a computer program that is designed to run on computer’s hardware and application programs). It performs preprocessing of the High Level Language (HLL). Preprocessing is the first step of the language processing system.
Sep 23, 2024 · In this phase, a program called the preprocessor makes various changes to the text of the code file. The preprocessor does not actually modify the original code files in any way -- rather, all changes made by the preprocessor happen either temporarily in-memory or using temporary files.
Dec 12, 2022 · A preprocessor is a utility that is run over code before it is compiled. Typically, a compiler will automatically call the preprocessor as it starts, however, they can also be run separately. The preprocessor’s job is to set up the code exactly as intended.
The C preprocessor is the macro preprocessor for several computer programming languages, such as C, Objective-C, C++, and a variety of Fortran languages. The preprocessor provides inclusion of header files, macro expansions, conditional compilation, and line control.
Jun 22, 2023 · Directives. The preprocessing directives control the behavior of the preprocessor. Each directive occupies one line and has the following format: # character. preprocessing instruction (one of define, undef, include, if, ifdef, ifndef, else, elif, elifdef, elifndef(since C23), endif, line, embed(since C23), error, warning(since C23), pragma) [1]
