Library Inclusion

In C++, library inclusion is the process of making external code available to your program. This is achieved primarily through the #include preprocessor directive, which allows you to incorporate header files containing declarations of functions, classes, and other entities. Header files from the standard library are included using angle brackets (<iostream>), while user-defined or third-party headers are included using double quotes ("myheader.h"). While less common, source files can also be included, though this practice is generally discouraged due to potential issues with multiple definitions and longer compile times.