Multiple inclusion of header files in C/C++ programming can lead to compilation errors and undefined behavior. A header file typically contains function declarations, macros, and other definitions that are included in multiple source files. If a header file is included more than once in the same compilation unit, the compiler may attempt to process the same declarations and definitions multiple times, resulting in errors or unexpected behavior.
To avoid multiple inclusion of header files, the preprocessor directives #ifndef and #define are commonly used. These directives allow you to define a preprocessor macro that is only defined once, even if the header file is included multiple times. The general pattern is as follows:
