Formalizing CIN

• cin >> var
  • Behaves differently depending on the type of variable
  • first skips whitespace
    • space, tab, carriage return
  • for char - reads the next non whitespace character
  • for string reads from a valid character up to the next whitespace
  • for int reads until a non digit is encountered.
  • for float reads until a non float character is found.
    • 3
    • 3.14
    • +3.14e15
    • +3.14e-15
  • NOTICE: you can mess things up with bad input. We do not yet have the tools to perform input validation.
• There are other input options.
• cin.get
  • \n is the character that is generated by the return key
  • \t by the tab key
  • We can read these with a function called cin.get(charvar)
  • This reads the next character from the input stream and puts it into charvar.
  • This will be much more useful later.
• cin.ignore
  • cin.ignore(int,char)
  • This will ignore up to the next (int) characters or until it finds a (char)
  • cin.ignore (5,'k')
• getline(stream, string)
  • Reads from stream and stores it into string until the next newline is found.
• Trace the following code
  • Input Stream: (assume § is the newline character)

    -------------------------
    |5  12  12e34 hello§
    |now is the time§
     
       
    
       
    
       
    
       
       int a;
       string b;
       char c;
       float d;
       
    
       
    Code 1
    Code 2
    
       
    
       
       cin >> a;
       cin >> b;
       cin >> c;
       cin >> d;
       cin >> b;
       cin.get(b);
       cin.get(b)
       getline(cin,b);
       
       
    
          
            cin >> d;
    	cin >> b;
    	cin >> a;
    	cin >> c;
    	cin >> b;
    	cin >> b;
    	cin >> c;