Contents

#include "phone_number.h"
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdio.h>

#define AREA_CODE_LENGTH         (3)
#define EXCHANGE_LENGTH          (3)
#define EXTENSION_LENGTH         (4)
#define VALID_NUMBER_LENGTH      AREA_CODE_LENGTH + EXCHANGE_LENGTH + EXTENSION_LENGTH
#define FORMATTED_LENGTH         VALID_NUMBER_LENGTH + 4

#define EXCHANGE_OFFSET (AREA_CODE_LENGTH)
#define EXTENSION_OFFSET (AREA_CODE_LENGTH + EXCHANGE_LENGTH)

#define INVALID_NUMBER_RESULT    "0000000000"

static void remove_leading_digit(char *phone_number)
{
   for (size_t i = 0; phone_number[i]; ++i) {
      phone_number[i] = phone_number[i + 1];
   }
}

char *phone_number_clean(const char *input)
{
   char *output = calloc(VALID_NUMBER_LENGTH + 2, sizeof(char));

   size_t j = 0;
   for (size_t i = 0; i < strlen(input); i++) {
      if (isdigit(input[i])) {
         if (j > VALID_NUMBER_LENGTH) {
            break;
         }
         output[j++] = input[i];
      }
   }

   if (j > 11 || j < 10) {
      strcpy(output, INVALID_NUMBER_RESULT);
   } else if (j == 11) {
      if (output[0] == '1') {
         remove_leading_digit(output);
      } else {
         strcpy(output, INVALID_NUMBER_RESULT);
      }
   }

   return output;
}

char *phone_number_get_area_code(const char *input)
{
   char *output = phone_number_clean(input);
   output[3] = '\0';

   return output;
}

char *phone_number_format(const char *input)
{
   char *cleaned_input = phone_number_clean(input);
   char *output = calloc(FORMATTED_LENGTH + 1, sizeof(char));

   sprintf(output, "(%.3s) %.3s-%.4s", cleaned_input,
           &cleaned_input[AREA_CODE_LENGTH], &cleaned_input[EXTENSION_OFFSET]);

   free(cleaned_input);

   return output;
}

Version data entries

3 entries across 3 versions & 1 rubygems

Version	Path
trackler-2.0.8.34	tracks/c/exercises/phone-number/src/example.c
trackler-2.0.8.33	tracks/c/exercises/phone-number/src/example.c
trackler-2.0.8.32	tracks/c/exercises/phone-number/src/example.c