In C, argc and argv are input parameters to the main() function, which is the entry point of a C program.

• argc stands for "argument count" and is an integer that indicates how many arguments were entered on the command line when the program was started. The value of argc is at least 1, because the first argument is always the name of the program itself.

• argv stands for "argument vector" and is an array of C-style strings (character arrays, with a null terminator) . It contains the actual arguments passed to the program on the command line, including the name of the program itself as the first argument. The elements of argv are pointers to the strings that represent the command-line arguments.

Together, argc and argv allow a C program to receive input from the command line. The number of arguments and their values can be used to control the behavior of the program. For example, a program that expects a filename as input can use argc to check that exactly one argument was provided, and use argv to access the filename string.