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For example, if you wanted to create a function named OpenFile, it might not compile correctly, because the header file <windows.h> defines the token OpenFile to map to either OpenFileA or OpenFileW (depending on if UNICODE is defined or not). The correct solution is to #undef OpenFile before defining your function.
25 sty 2015 · #define should be read as replacing any potential previous definition, but not to imply that it must already be defined. Popular compilers do allow you to skip the #undef , but this is not allowed by the official standard ISO C and C++ language specifications.
14 lip 2023 · In C programming, #define is a preprocessor directive that is used to define macros. The macros are the identifiers defined by #define which are replaced by their value before compilation. We can define constants and functions like macros using #define.
17 wrz 2024 · This example shows how to use #undef to remove a macro definition and redefine it later in the program. Code: #include <stdio.h> // Define a macro for maximum value #define MAX 100 int main() { printf("The maximum value is: %d\n", MAX); // Undefine the MAX macro #undef MAX // Redefine the MAX macro #define MAX 200 printf("The redefined maximum ...
A function consist of two parts: Declaration: the function's name, return type, and parameters (if any) Definition: the body of the function (code to be executed) void myFunction () { // declaration. // the body of the function (definition) }
9 paź 2022 · A C function is generally defined and declared in a single step because the function definition always starts with the function declaration so we do not need to declare it explicitly. The below example serves as both a function definition and a declaration.
This C Tutorial explains #define Directive in a C Program. #define directives are preprocessor directives. These are either symbolic constants or macros or conditional compilation constructs or other various directives. Let’s see first symbolic constants, for ex., #define NAME "What is your name?"
