Objective-C Displaying Numbers as Words Using Math - objective-c

Question

I have an exercise in my Objective-C book in which I must design a program using only the knowledge the book has given me so far to do so. It tells me to use math to do this not any methods from Objective-C.
What I must do is get any integer from the user and then convert each number to a word.
For example if the user enters: 956
The output must then be:
nine
five
six
I am not the best math student and definitely need help here. I can of course use loops of any kind as well as if statements and basic math operators as well as arrays but no built in methods.
I assume that I need to get each digit separated into its own integer variable and then use switch of if statements to then create the strings and display them but cannot successfully do this.
Please help, thanks!

Answer 1

Here's an example I quickly came up with. See the comments in the code below for an explanation.
//Create an array of number strings. They must be in order starting from 0 so the indexes line up
NSArray *numbers = #[#"zero", #"one", #"two", #"three", #"four", #"five", #"six", #"seven", #"eight", #"nine"];
//Create whatever string you're processing
NSString *numString = #"956";
//Loop through the substrings of the number string
while (numString.length > 0) {
//Get the first character in the string
int currentNum = [[numString substringToIndex:1] intValue];
//Print the number. The number string should be at the index of this value in the array
NSLog(#"%#", numbers[currentNum]);
//Remove everything before the first character
numString = [numString substringFromIndex:1];
}
Output:
nine
five
six

Answer 2

Here is a working example using C (one of your tags):
This one makes use of a char *[] (array of C strings) and ascii values of each char...
char *number[]={"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"};
int main(void)
{
char dig[20];
int len, i;
printf("enter integer: "); //instruction to user
scanf("%s", dig); //read from user
len = strlen(dig);
for(i=0;i<len;i++)
{
if(isdigit(dig[i]))//test to verify good user input (accept only digits)
{
printf("%s\n", number[dig[i]-48]); // 48-57 is range of ASCII values for 0-9
}
}
return 0;
}
Example session: