Thread: newbie coding problem

Why not just use -1 to end, since the program is meant to change the case to upper and lower then the program should stop or at least print an error message when it encounters a non alphabetic character.

Code:

// upper lower case conversion prblm 1 pg 137
#include <iostream>
#include <cctype>

using namespace std;

int main(void)
{
  char ch;
  cout<<"Changes lower case to upper and upper to lower case.\n";
  cout<<"Enter a phrase (-1 to exit):";
  cin.get(ch);
  while(ch != '-1'){
    if(isalpha(ch)){
      if(islower(ch))
        ch=toupper(ch);
      else
        ch=tolower(ch);
      cout<<ch<<flush;
    }else{
      cout<<"input not valid!"<<flush;
    cin.get(ch);
  }
  return 0;
}