Using seperate elements in a string array?

Sorry in advance for the wordiness

This is for a homework assignment, so i'm not asking for help on the entire thing , though i'm not a CS major, so it really rustles my jimmies.
The code is supposed to convert a number into words (ie 23 into twenty three)

so far, the user inputs an int, i use sprintf to write it to a char array, then send it to a function that is supposed to convert it.

Code:

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

int getNumber();
char convertToString(char *buffer);

int main()
{
    char *buffer[100];
    int num;

    num = getNumber();
    memset(buffer, '\0', 100);
    sprintf(buffer,"%d",num);

    printf("You typed: %s \n",buffer); //test

    convertToString(buffer);


    return 0;

}

int getNumber(){

    int num;

    do{
       printf("Enter an integer less than 1000: ");
       scanf("%d",&num);
    }while(num<1 || num>999);

    return(num);
}

char convertToString(char *buffer)
{
    char *ones[]={"one ","two ","three ","four ","five","six ","seven ","eight ","nine "};
    char *tens[]={"ten ","eleven ","twelve ","thirteen ","fourteen ","fifteen ","sixteen ","seventeen ","eighteen ","nineteen "};
    char *twenties[]={"","twenty ","thirty ","forty ","fifty ","sixty ","seventy ","eighty ","ninety "};
    char *hundreds[]={"","","one hundred ","two hundred ","three hundred ","four hundred ","five hundred ","six hundred ","seven hundred ","eight hundred ","nine hundred "};

    char *temp[100];
    int length = strlen(buffer);

    if(length = 1)
    {
        strcpy(temp,ones[buffer[0]]);
    }
}

Not finished yet obviously, but I hit a problem on the line with:
strcpy(temp,ones[buffer[0]]);
which is supposed to take what's in buffer[0] (the first digit of the inputted number), and tell it to copy the same index of ones (so if buffer[0] = 3, ones[buffer[0]] = three, then copy it into my temp array, which integers of length 2 or 3 would be catenated to the end.

BUT, if the user inputted number was say 34, buffer[0]=3 as i would expect, but buffer[1] is garbage. How can I fix this so the separate digits of the inputted number are in separate elements of the buffer array? Or is there an easier way to do this...?

Before you convert the number to a string, I'd "range" the number, so if you had a number like twenty two, you wouldn't have to parse out whether it was a twelve or not, later on. (since they both begin with "tw").

Look for an _itoa() function or you can code your own easy enough. It's not standard C, but mine is located in stdlib.h, which your program would need to include.

BUT, if the user inputted number was say 34, buffer[0]=3 as i would expect, but buffer[1] is garbage.

Wrong on both accounts.

The string "34" is composed of three character values '3', '4', and '\0'. The value '3' may or may not equal the numeric value 3.

You are essentially parsing a string for a value and then immediately serializing that value back to a string.

Soma

i got it working, thanks for the input