What is the use of conditional preprocessor directive in C?
A conditional is a directive that instructs the preprocessor to select whether or not to include a chunk of code in the final token stream passed to the compiler.
What is the purpose of the preprocessing directive?
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.
Is Elif used in C?
In the C Programming Language, the #elif provides an alternate action when used with the #if, #ifdef, or #ifndef directives. The #elif directive can be thought of as #else if.
What is the purpose of #ifndef?
#ifndef and #define are known as header guards. Their primary purpose is to prevent C++ header files from being included multiple times.
What is #ifndef #define and #endif used for?
#ifndef checks whether the given token has been #defined earlier in the file or in an included file; if not, it includes the code between it and the closing #else or, if no #else is present, #endif statement.
What do you understand by conditional compilation directives describe any 3 conditional compilation directives with the help of examples?
A preprocessor conditional compilation directive causes the preprocessor to conditionally suppress the compilation of portions of source code. The #ifdef directive, which conditionally includes source text if a macro name is defined. …
What is the purpose of preprocessor?
In computer science, a preprocessor (or precompiler) is a program that processes its input data to produce output that is used as input to 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.
What is the purpose of #ifndef and its associated #define and #endif?
What is else if ladder in C?
In C/C++ if-else-if ladder helps user decide from among multiple options. The C/C++ if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the C else-if ladder is bypassed.
What is Ifdef and Ifndef?
ifdef means “if the following is defined” while ifndef means “if the following is not defined”.
Should I use Pragma once or Ifndef?
From a software tester’s perspective. #pragma once is shorter than an include guard, less error prone, supported by most compilers, and some say that it compiles faster (which is not true [any longer]). But I still suggest you go with standard #ifndef include guards.