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What is a pre compiler directive?

What is a pre compiler directive?

Preprocessor directives are lines included in a program that begin with the character #, which make them different from a typical source code text. They are invoked by the compiler to process some programs before compilation.

What is the use of pre processor directives?

Preprocessor directives, such as #define and #ifdef , are typically used to make source programs easy to change and easy to compile in different execution environments. Directives in the source file tell the preprocessor to take specific actions.

What are pre processor directives give examples?

Examples of some preprocessor directives are: #include, #define, #ifndef etc. Remember that # symbol only provides a path that it will go to the preprocessor, and command such as include is processed by preprocessor program. For example, include will include extra code to your program.

Why and when do we use #define and #include directive?

In a C Program, we generally write all the preprocessor directives outside the main() function, at the top of our C program. #define directive is used to define constants or an expression in our C Program, while #include directive is used to include content of header files in our C program.

Why preprocessing directives are used eg #include Iostream?

The #include directive allows a programmer to include contents of one file inside another file. This is commonly used to separate information needed by more than one part of a program into its own file so that it can be included again and again without having to re-type all the source code into each file.

Which of the following options would you use to define pre processor?

For ans [A]. #define is a preprocessor directive.

Why the define directive is used?

The #define directive is used to define values or macros that are used by the preprocessor to manipulate the program source code before it is compiled. Because preprocessor definitions are substituted before the compiler acts on the source code, any errors that are introduced by #define are difficult to trace.

What are the two forms of #include directive?

Here are the two types of file that can be included using #include: Header File or Standard files: This is a file which contains C/C++ function declarations and macro definitions to be shared between several source files.

Why do you need a linker?

The linker copies all library routines used in the program into executable image. As a result, it requires more memory space. As it does not require the presence of library on the system when it is run, so it is faster and more portable.

What are the roles of preprocessor directives in the compilation of a C++ program?

The preprocessors are the directives, which give instructions to the compiler to preprocess the information before actual compilation starts. All preprocessor directives begin with #, and only white-space characters may appear before a preprocessor directive on a line.

Which of the following options would you use to define preprocessor?

What are preprocessor directives?

The preprocessor directives give instruction to the compiler to preprocess the information before actual compilation starts. All preprocessor directives begin with #, and only white-space characters may appear before a preprocessor directive on a line. Preprocessor directives are not statements, so they do not end with a semicolon (;).

Do preprocessor directives start with a semicolon?

All preprocessor directives begin with #, and only white-space characters may appear before a preprocessor directive on a line. Preprocessor directives are not statements, so they do not end with a semicolon (;).

What is the use of define in preprocessor?

The #define preprocessor directive creates symbolic constants. #define lets you define a symbol such that, by using the symbol as the expression passed to the #if directive, the expression evaluates to true. Conditional Directives. You can use the #if directive to create a conditional directive.

Is there a preprocessor in C compiler?

C# compiler does not have a separate preprocessor; however, the directives are processed as if there was one. In C# the preprocessor directives are used to help in conditional compilation.