//John T. Rine
//September 10, 2011

#include<stdio.h>
#include<stdlib.h>

int cntChars(char *);
char *insert(char, char *, int);

int main(int argc, char **argv)
{
	char temp = 127, temp2;
	int number;
	char *ptrChar;
	int count;

	if (argc == 1) printf("Should be at least one command line argument supplied after the file name\n");
	else
	{
		printf("Enter a character to append to the string supplied on the command line\n");
		temp = getchar();
		getchar();	//flush!!!
		printf("Enter a number representing the position in which to place the character\n");
		temp2 = getchar();
		getchar();	//flush!!!
		number = temp2 - 48;
		printf("%s\n", ptrChar = insert(temp, *(argv + 1), number));
		free(ptrChar);
	}

	return(0);
}

int cntChars(char *inputString)
{
	// returned value "count" does not include '\0'
	int count = 0;
	while(*(inputString + count) != '\0') ++count;
	return(count);
}

char *insert(char inputChar, char *inputString, int position)
{
	//element      0    1    2
	//count = 0   '\0'
	//count = 1    A   '\0'
	//count = 2    M    y   '\0'

	int count, i;
	char * pChar;

	count = cntChars(inputString);
	if (!(pChar = (char *) malloc(sizeof(char) * (count + 2))))
	{
		fprintf(stderr,"Insufficient memory");
		exit(1);  
	}
	else
	{
		i = 0;
		while(i <= (count + 1))
		{
			if(i < position) *(pChar + i) = *(inputString + i);
			else if	(i == position) *(pChar + i) = inputChar;
			else *(pChar + i) = *(inputString + i - 1);
			i++;
		}
		return(pChar);
	}
}