Validating User Input String - c

Question

Here's part of the description of the assignment: The program must stop
accepting input when the user enters the word done. Assume that no word is
more than 20 letters long.
I have to validate that if a word is more than 20 characters thy will get an error message and have to retype again. Also when I type done, the program should end. Im not sure how to write these statements correctly. When I run it and type more then 20 characters it gives me an error - Expression: L("Buffer is too small" &&0)
Here's my Code so far:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXCHAR 20
int charcount(char []);
int main()
{
char message[MAXCHAR];
int numofchar;
printf("Enter any word to display how many characters that word has.\nA word CANNOT be more than 20 charatcers long.\n");
printf("When you are finished type the word done.\n");
do
{
printf("\nEnter a word: " );
gets_s(message, MAXCHAR);
numofchar = charcount(message);
while ( numofchar > MAXCHAR)
{
printf("The word enterd is more then 20 characters. Try again.\n");
printf("Enter a word: " );
gets_s(message, MAXCHAR);
}
printf("The word %s has %d characters.\n", (message),numofchar);
} while ( (message,MAXCHAR) != 'done');
printf("\nEnd of program.\n");
system ("PAUSE");
return 0;
}
int charcount (char list[])
{
int i, count = 0;
for(i = 0; list[i] != '\0'; i++)
count++;
return(count);
}

Answer 1

To detect an error, you simply need to check the return value of get_s:
http://msdn.microsoft.com/en-us/library/5b5x9wc7%28v=vs.90%29.aspx
int main()
{
char message[MAXCHAR], *s;
int numofchar;
...
do
{
printf("\nEnter a word: " );
s = gets_s(message, MAXCHAR);
if (!s) {
<< some error handling code goes here >>
...