What does the program do?

What does this program do? #include #include #define USAGE "Please enter an integer as a command-line argument. " void mystery(int input) { int copy = input; int length = 0; while (copy) { ++length; copy >>= 1; } char output[length + 1]; output[length] = '\0'; char * current = output + (length - 1); while (input) { *current-- = (input & 1) + '0'; input >>= 1; } printf("%s ", output); } int main(int argc, char * argv[]) { if (argc != 2) { printf(USAGE); exit(EXIT_FAILURE); } mystery (atoi (argv[1])); return EXIT_SUCCESS; } It does not do anything, because it cause a segmentation fault where the mystery function allocates an array of char. It prints out the binary representation of the integer entered as the command-line argument. It prints out a random number. It prints out the hexadecimal representation of the integer entered as the command-line parameter