Thread: Problem with my program i cant figure out...

Ive been trying to get this program to work for the past two days and i cant seem to find whats wrong with it. bear, with me if its very obvious for you guys but a little hint would be much appreciated.

the purpose of this program is to check if user inputted character is a vowel or consonant in the Hawaiian language. the program is split into three different files, a header file, a .c file for two functions, and a driver.c file to test the functions. oh, and also a makefile to execute the program.

here is the header file

Code:

/* header file for letters.c */

int is_vowel(char ch);

int is_consonant(char ch);

#define TRUE 1
#define FALSE 0

and the .c file for the int is_vowel and int is_consonant functions.

Code:

/* functions that test if a character is a vowel or consonant in the hawaiian language. */

#include "letters.h"

int is_vowel(char ch)
{
        switch(ch)
         {
                case 'a': return TRUE;
                        break;
                case 'A': return TRUE;
                        break;
                case 'e': return TRUE;
                        break;
                case 'E': return TRUE;
                        break;
                case 'i': return TRUE;
                        break;
                case 'I': return TRUE;
                        break;
                case 'o': return TRUE;
                        break;
                case 'O': return TRUE;
                        break;
                case 'u': return TRUE;
                        break;
                default: return FALSE;
        }
}

int is_consonant(char ch)               
{
        switch(ch)
         {
                case 'h': return TRUE;
                        break; 
                case 'H': return TRUE;
                        break; 
                case 'k': return TRUE;
                        break;
                case 'K': return TRUE;
                        break;
                case 'l': return TRUE;
                        break; 
                case 'L': return TRUE;
                        break; 
                case 'm': return TRUE;
                        break; 
                case 'M': return TRUE;
                        break; 
                case 'n': return TRUE;
                        break; 
                case 'N': return TRUE;
                        break; 
                case 'p': return TRUE;
                        break; 
                case 'P': return TRUE;
                        break; 
                case 'w': return TRUE;
                        break; 
                case 'W': return TRUE;
                        break; 
                case '`': return TRUE;
                        break; 
                default: return FALSE;
        }
}

and the driver.c to test the two functions

Code:

/* driver to test letters.c */

#include "letters.h"
#include <stdio.h> 
#define FLUSH while(getchar() != '\n');

main()
{
   char ch;

        printf("Please enter a Hawaiian letter to be tested for being either a vowel or consonant:");
        
        while( (ch = getchar()) != EOF )
         {   
                if( is_vowel(ch) == TRUE )
                  printf("The character is a vowel\n");
                else
                  printf("The character is not a vowel or consonant\n");

                if( is_consonant(ch) == TRUE )
                  printf("The character is a consonant");
                else
                  printf("The character is not a vowel or consonant\n");
        
                printf("Please enter the next character to be tested\n");
        FLUSH
        } 
}

the problem i am having is whenever i compile and run the program and type in say the vowel "a", the program prints both "the character is a vowel" and "The character is not a vowel or consonant" statement. it does the same if the letter is a consonant.

....idk whats wrong????

Edit: just noticed, sorry for using an implicit main.