I have tested this program in my code block, it is working fine.

#include
char choice;
void main( )
{
while(1){
        /* Printing the available options */
        printf(\"Enter an alphabet\n\");

        /* Taking users input */
        scanf(\"%c\", &choice);

        switch(choice)
        {
            case 'a':
                printf(\"FALSE\");
                break;
            

            case 'e':
                printf(\"FALSE\");
                break;
            

            case 'i':
                printf(\"FALSE\");
                break;
            

            case 'o':
                printf(\"FALSE\");
                break;
           

            case 'u':
                printf(\"FALSE\");
                break;
         

            default:
                printf(\"TRUE\n\");
    }
scanf(\"%c\", &choice);
}

}