Main () Master Each C program must have a main () function, you can put it in a place in the program according to your hobby. Some of the programmers put it in front, while others put it in the end, no matter which place, the following description is suitable. 1. Main () parameter During the Turbo C2.0 startup process, pass the main () function three parameters: Argc, Argv, and ENV. * Argc: integer, for the number of command line parameters transmitted to main (). * Argv: string array. In the DOS 3.x version, Argv [0] is a full path name running; a version of DOS 3.0 or less, Argv [0] is an empty string ("). Argv [1] is the first string after executing the program name in the DOS command line; Argv [2] is the second string after executing the program; ... Argv [Argc] is NULL. * ENV: An array array. Each element of ENV [] includes a string in the form of envvar = value. Where ENVVAR is environment variable such as PATH or 87. Value is the correspondence value of Envvar as C: / DOS, C: / Turboc (for PATH) or YES (for 87). Turbo C2.0 always passes these three parameters to the main () function, which can be described (or not) in the user program, if some (or all) parameters are described, they become main () Local variable of the program. Note: Once you want to explain these parameters, you must press the order of Argc, Argv, ENV, as follows: Main () main (int Argc) main (int Argc, char * argv []) main (int Argc, char * Argv [], char * ENV []) The second case is legal, but not common, because there are very few only ARGCs in the program without the case of Argv [].
