Hi everyone,

I'm still new to C, coming from a Python background, and I was wondering if you could suggest any ways to improve/shorten my code. It's for a first-year university assignment, but I've already got it working and golfed it a bit on my own. Here it is:

Code:
#include<stdio.h>
#include <ctype.h>
int main(void) {
  char c = '\0';
  int vowelCount = 0, conCount = 0;
  while (c != '0') {
    puts("\nPlease enter a letter: ");
    scanf(" %c", &c);
    if (isalpha(c) || c == '0') {
      switch (tolower(c)) {
        case '0':
          puts("\nThank you for counting on me.");
          continue;
        case 'a':
        case 'e':
        case 'i':
        case 'o':
        case 'u':
          vowelCount++;
          for (int i = 0; i < vowelCount; i++) {
            putchar('*');
          }
          break;
        default:
          conCount++;
          for (int i = 0; i < conCount; i++) {
            putchar('!');
          }
        }
    }
    else {
      puts("\nAny character not in the English alphabet is not an accepted input for this application.\n");
    }
  }

}
Any comments welcome!