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The C preprocessor (used with C, C++ and in other contexts) defines an include directive as a line that starts #include and is followed by a file specification. COBOL defines an include directive indicated by copy in order to include a copybook. Generally, for C/C++ the include directive is used to include a header file, but can
However, C is not a subset of C++, [3] and nontrivial C programs will not compile as C++ code without modification. Likewise, C++ introduces many features that are not available in C and in practice almost all code written in C++ is not conforming C code. This article, however, focuses on differences that cause conforming C code to be ill ...
In C++, associative containers are a group of class templates in the standard library of the C++ programming language that implement ordered associative arrays. [1] Being templates , they can be used to store arbitrary elements, such as integers or custom classes.
For #include guards to work properly, each guard must test and conditionally set a different preprocessor macro. Therefore, a project using #include guards must work out a coherent naming scheme for its include guards, and make sure its scheme doesn't conflict with that of any third-party headers it uses, or with the names of any globally visible macros.
The #include directive is defined to represent a programmer's intention to actually include the text of a file at the point of the directive. This may occur several times within a single compilation unit, and is useful for evaluating macro-containing contents multiple times against changing definitions of the macro.
In C++, a constructor of a class/struct can have an initializer list within the definition but prior to the constructor body. It is important to note that when you use an initialization list, the values are not assigned to the variable. They are initialized. In the below example, 0 is initialized into re and im. Example:
Python has two directives – from __future__ import feature (defined in PEP 236 -- Back to the __future__), which changes language features (and uses the existing module import syntax, as in Perl), and the coding directive (in a comment) to specify the encoding of a source code file (defined in PEP 263 -- Defining Python Source Code Encodings).
A function pointer, also called a subroutine pointer or procedure pointer, is a pointer referencing executable code, rather than data. Dereferencing the function pointer yields the referenced function, which can be invoked and passed arguments just as in a normal function call.