C language Program extract help

startPos = strlen(MyInput);
			do {
		startPos = startPos - 3;
				if (startPos < 0) {
				numdigits = numdigits + startPos;
				startPos = 0;
					}
				strncpy(threedigits, MyInput + startPos, numdigits);
				threedigits[numdigits] = '\0';
			printf("%s ",threedigits);

Code (markup):

Hello DP, really need your help.
This code snippet extract the Input number by 3digits. So for example I input 123456789, it will look like this 789 567 123 >> How could I get the 1st entry in order for it to perform the processing of converting those number to words and so on so forth. I'm a newbie in C language.

 

dont you think out put you think should be 789 456 123 ??

 

Oh I am very sorry. Yeah you are right, if I input 123456789 the outcome of the code snippet will be 789 456 123. How could process this output in order to give them values in words? Really need your help. Thanks.

 

will send you a function for the same !!

 

yes thank you. I wait for your reply.