#include <stdio.h>
#include <string.h>

#define WORDS_LEN       1000
#define INPUT_LEN       4
#define MAX_DIGITS      3

void getInput(char *input);
void getDigits(char *input, int *hundreds, int *tens, int *ones);
void convertToString(char *input, char *words);
void convertHundreds(int hundreds, char *words);
void convertTens(int tens, char *words);
void convertTeens(int tens, int ones, char *words);
void convertOnes(int tens, int ones, char *words);

int main() {
        char input[INPUT_LEN];
        char words[WORDS_LEN];

        getInput(input);
        printf("Value entered was %s \n", input );

        convertToString(input,words);
        printf("Conversion to words is \n%s \n", words );

        return 0;
}

void getInput(char *input) {

        printf("Please input an integer value between 1 less than 1000\n");
        fgets(input,INPUT_LEN,stdin);

        char *nl = strchr(input,'\n');
        if (nl != 0)
                *nl = 0;

        return;
}

void getDigits(char *input, int *hundreds, int *tens, int *ones) {

        int digits[MAX_DIGITS] = { 0, 0, 0 };

        int numDigits = strlen(input)-1;
        int curDigit = MAX_DIGITS-1;

        int i;
        for (i=numDigits; i>= 0; i--,curDigit--) {
                digits[curDigit] = input[i]-'0';
//              printf("digit %d %d is %d \n", i, curDigit, input[i]-'0');
        }

        *hundreds = digits[0];
        *tens = digits[1];
        *ones = digits[2];

        return;
}

void convertToString(char *input, char *words) {

        int hundreds, tens, ones;

        getDigits(input, &hundreds, &tens, &ones);

        words[0] = 0;
        convertHundreds(hundreds,words);
        convertTens(tens,words);
        convertTeens(tens,ones,words);
        convertOnes(tens,ones,words);

        return;
}

void convertHundreds(int hundreds, char *words) {

        char *strings[10] = { "", "one", "two", "three", "four", "five",
                              "six", "seven", "eight", "nine" };

        if (hundreds < 1) return;

        strncat(words, strings[hundreds], WORDS_LEN);
        strncat(words," hundred ", WORDS_LEN);

        return;
}

void convertTens(int tens, char *words) {

        char *strings[10] = { "", "", "twenty", "thirty", "forty", "fifty",
                              "sixty", "seventy", "eighty", "ninety" };

        if (tens <2) return;

        strncat(words,strings[tens],WORDS_LEN);
        strncat(words,"-",WORDS_LEN);

        return;
}

void convertTeens(int tens, int ones, char *words) {

        char *strings[10] = { "tens", "eleven", "twelve", "thirteen", "fourteen", "fifteen",
                              "sixteen", "seventeen", "eighteen", "nineteen" };

        if (tens != 1) return;

        strncat(words, strings[ones], WORDS_LEN);

        return;
}

void convertOnes(int tens, int ones, char *words) {

        char *strings[10] = { "", "one", "two", "three", "four", "five",
                              "six", "seven", "eight", "nine" };

        if (tens == 1) return;

        strncat(words, strings[ones], WORDS_LEN);

        return;
}