# C > Small Programs Code Examples

## Positional notation of numbers

``` Positional notation of numbers #include <stdio.h> #include <math.h> #define PACKAGE "digits" int number_of_digits(int x); void print_help(void); int main(int argc, char *argv[]) { int n; /* input; the number to convert */ short base; /* input; base to which we will convert n */ short rhdigit; /* right-hand digit of n-prime */ int power; /* loop */ if(argc != 3) { print_help(); return 1; } else { sscanf(argv[1], "%d", &n); if(n < 1) { fprintf(stderr, "%s: Error: Number must be greater than 0.\n", PACKAGE); return 1; } sscanf(argv[2], "%hi", &base); if(base < 2 || base > 10) { fprintf(stderr, "%s: Error: Base is not in required range.", PACKAGE); return 1 ; } } /* else */ printf("The number %d, is %d wide, ", n, number_of_digits(n)); printf("and contains the numbers: "); /* // Generate digits of converted number, right to left. */ for(power = 0; n != 0; power++) { rhdigit = n % base; /* Isolate right-hand digit of n. */ n /= base; /* then eliminate right-hand digit. */ printf("%hi ", rhdigit); } printf("\n"); return 0; } int number_of_digits(int x) { return x ? (int)(log10((double)(abs(x))))+1 : 1; } void print_help(void) { fprintf(stdout, "Usage : %s [NUMBER] [BASE]\n", PACKAGE); fprintf(stdout, "Example: %s 4591 10\n", PACKAGE); } ```