argvargc

argvargc refers to the two parameters passed to the main function in C and C++ programs that expose the program’s command-line arguments at runtime. argc is an int counting how many command-line arguments were provided, and argv is an array of pointers to strings (char* or char**). The array has argc elements plus a terminating NULL, and argv[0] is the program name or path as invoked by the host environment.

Typical main signatures include int main(int argc, char* argv[]) or int main(void) in C, and int main(int argc, char* argv[]) or int main() in C++. In hosted environments, argc is at least 1 because argv[0] contains the program’s name or path.

Usage involves inspecting argc to determine how many arguments were supplied and referring to argv[i] for each argument. argv[1] through argv[argc-1] are the user-provided arguments. Developers often convert these strings to numbers using functions like strtol or strtod, with proper error checking. Example: int main(int argc, char* argv[]) { if (argc > 1) printf("First arg: %s\n", argv[1]); return 0; }

Portability and conventions vary by platform, but the general concept is ubiquitous in command-line interfaces. On Unix-like systems, argv[0] typically holds the program path; on Windows, it may be just the executable name. argv[argc] is guaranteed to be NULL, enabling safe iteration patterns.

Common pitfalls include accessing argv beyond argc, assuming specific argument formats, and neglecting input validation or encoding issues. For complex option parsing, programmers often rely on libraries or standards such as getopt (POSIX) or higher-level argument parsers in various languages.

See also command-line interface, getopt, argument vector, argument count.