// accept input
// remove trailing newline and replace with null character '\0'
int string_length = strlen( my_string ) ;
if( my_string[string_length - 1] == '?' || 
                          my_string[string_length - 1] == '!' )
{
    // continue with the normal functionning
}
else
{
    // duck out of program, using return 1 or exit(1) or again 
   // ask for user input
}

while( ! isalpha( character ) )
{
    // skip the character and move on
}