convert_a_number_into_words.c

/*PROGRAM TO CONVERT A NUMBER INTO WORDS*/
#include<stdio.h>
#include<string.h>
void convert(char *num){
    int len=strlen(num); //i.e. find no of digit
    /*no number*/
    if (!len){
    fprintf(stderr,"empty string\n");
    return;
    }
    char *single_digits[]={"zero","one","two","three","four","five","six","seven","eight","nine"};
    char *two_digits[]={"","ten","eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen"};
    char *tens_multiple[]={"","","twenty","thirty","forty","fifty","sixty","seventy","eighty","ninety"};
    char *tens_power[]={"hundred","thousand"};
    /*single number*/
    if (len==1){
    printf("%s\n",single_digits[*num-'0']);
    return;
    }
    while (*num!='\0'){
        if (len>=3){
        if (*num-'0'!=0) {
        printf("%s ",single_digits[*num-'0']);
        printf("%s ",tens_power[len-3]); //i.e. here len can be 3 or 4
        }
        --len;
        }
        /*code path for last 2 digits*/
        else{
        if (*num=='1'){
        int sum=*num-'0'+*(num+1)-'0';
        printf("%s\n",two_digits[sum]);
        return;
        }
        else if(*num=='2'&&*(num+1)=='0'){
        printf("twenty\n");
        return;
        }
        /*number range 21 to 99*/
        else{
        int i=*num-'0';
        printf("%s ",i?tens_multiple[i]:"");
        ++num;
        if (*num!='0')
        printf("%s ",single_digits[*num-'0']);
        }
        }
        ++num;
    }
}
void main(){
    char a[10];
    printf("\nEnter the number: ");
    scanf("%s",a);
    printf("\nThe number in word is: ");
    convert(a);
}