# [[C++]] Compiler needs to know about functions before they are used - Define function before calling - works in a pinch - not as scalable - Use function prototypes - Provides necessary information to compiler without full function definition - "Forward declarations" - Placed at beginning of program - header files ```c int function_name(); // prototype int function_name(int); int function_name(int a); int function_name () { // full definition return 0; } # Prototypes Compiler needs to know about functions before they are used - Define function before calling - works in a pinch - not as scalable - Use function prototypes - Provides necessary information to compiler without full function definition - "Forward declarations" - Placed at beginning of program - header files ```c int function_name(); // prototype int function_name(int); int function_name(int a); int function_name () { // full definition return 0; } ```