Input checking with English Measure class - C++ File Stream

C++ examples for File Stream:cin

  1. HOME
  2. C++
  3. File Stream
  4. cin

Description

Input checking with English Measure class

Demo Code

#include <iostream>
#include <string>
#include <cstdlib>                //for atoi(), atof()
using namespace std;
int isFeet(string);               //declaration
class Measure//from  ww w.ja v a  2s.co  m
{
   private:
   int feet;
   float inches;
   public:
   Measure()
   { feet = 0; inches = 0.0; }
   Measure(int ft, float in)
   { feet = ft; inches = in; }
   void showdist()
   { cout << feet << "\'-" << inches << '\"'; }
   void getdist();             //get length from user
};
void Measure::getdist()          //get length from user
{
   string instr;
   while(true)                    //cycle until feet are right
   {
      cout << "\n\nEnter feet: ";
      cin.unsetf(ios::skipws);    //do not skip white space
      cin >> instr;               //get feet as a string
      if( isFeet(instr) )         //is it a correct feet value?
      {                        //yes
          cin.ignore(10, '\n');    //eat chars, including newline
          feet = atoi( instr.c_str() );  //convert to integer
          break;
      }                        //no, not an integer
      cin.ignore(10, '\n');       //eat chars, including newline
      cout << "Feet must be an integer less than 1000\n";
    }
    while(true)                    //cycle until inches are right
    {
       cout << "Enter inches: ";
       cin.unsetf(ios::skipws);    //do not skip white space
       cin >> inches;              //get inches (type float)
       if(inches>=12.0 || inches<0.0)
       {
          cout << "Inches must be between 0.0 and 11.99\n";
          cin.clear(ios::failbit); //"artificially" set fail bit
       }
       if( cin.good() )            //check for cin failure
       {                        //(most commonly a non-digit)
           cin.ignore(10, '\n');    //eat the newline
           break;                   //input is OK, exit 'while'
       }
       cin.clear();                //error; clear the error state
       cin.ignore(10, '\n');       //eat chars, including newline
       cout << "Incorrect inches input\n";  //start again
    }
}
int isFeet(string str)
{
    int slen = str.size();         //get length
    if(slen==0 || slen > 5)        //if no input, or too long
    return 0;                   //not an int
    for(int j=0; j<slen; j++)      //check each character
        //if not digit or minus
        if( (str[j] < '0' || str[j] > '9') && str[j] != '-' )
            return 0;                //string is not correct feet
    double n = atof( str.c_str() );  //convert to double
    if( n<-999.0 || n>999.0 )      //is it out of range?
        return 0;                   //if so, not correct feet
    return 1;                      //it is correct feet
}
int main()
{
    Measure d;
    char ans;
    do
    {
        d.getdist();
        cout << "\nMeasure = ";
        d.showdist();
        cout << "\nDo another (y/n)? ";
        cin >> ans;
        cin.ignore(10, '\n');       //eat chars, including newline
    } while(ans != 'n');        //cycle until 'n'
    return 0;
}

Result


Related Tutorials