Explain what \"#include \" does in a source code? Solution The \"# include\" statement \"grabs the attention\" of the pre-processor (the process that occurs before your program is actually compiled) and \"tells\" the pre-processor to include whatever follows the \"# include\" statement. While the pre-processor can be told to do quite a bit, in this instance it\'s being asked to recognize a header file (which is denoted with a \".h\" following the name of that header, indicating that it\'s a header). Simpler words: The preprocessor reads the primary source file into memory, and scans for commands such as #include. ... The directive is for the preprocessor, which actually has very little to do with the C compiler except that they are always bundled togethe.