Simple program problem from upper to lower case

This is a discussion on Simple program problem from upper to lower case within the C++ Programming forums, part of the General Programming Boards category; My homework is to create a program that changes an Uppercase letter to a lower case letter. My teacher has ...

  1. #1
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    Simple program problem from upper to lower case

    My homework is to create a program that changes an Uppercase letter to a lower case letter. My teacher has not introduced the tolower function, so I am not using it. We were also required to use the cout.put and cin.get functions. Anyway, my program works but when I send it through my teachers automated assignment checker I get 2 warnings (this will cost me points). The warnings are as follows:

    Source 1.cpp(39) : warning C4244: 'argument' : conversion from 'int' to 'char', possible loss of data

    and

    cout.put((int)myLower); // cout.put outputs char found by myUpper + TOLOWER
    Source 1.cpp(39): error 734: (Info -- Loss of precision (arg. no. 1) (31 bits to 7 bits))

    Here is my code. Thank you for help in advance:

    Code:
    #include <iostream>
    #include <cstdlib>
    using namespace std;
    
    
    int main()
    {
       int myUpper;                                    // declares myUpper an integer allowing us to use const char TOLOWER
       int myLower;
       const int TOLOWER = ' ';                        // initializes TOLOWER to ' ' which has decimal value of 32
       
       cout << "Please Enter an Upper Case Letter: ";  // asks user for myUpper
       myUpper = cin.get();                            // cin.get takes first character entered by user
       myLower = myUpper + TOLOWER;                    // add value of 32 to upper case decimal value to find a lower case
       
       cout << "\nYour Lower Case Letter is: ";
       cout.put((int)myLower);                         // cout.put outputs char found by myUpper + TOLOWER
       cout << "\n\n";                                 // newlines entered for clarity
    
       return(EXIT_SUCCESS);
    }

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    Are you aware of the char variable type?

  3. #3
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    Quote Originally Posted by Daved View Post
    Are you aware of the char variable type?
    It doesn't matter since cin.get() returns an int and cout.put() takes a char, he will have a warning whichever way he declares the variable.

    If you just want to get rid of the warning, you can do a cast:
    Code:
    cout.put(static_cast<char>(myLower));
    If you want to avoid casts altogether, you can get input using ">>" instead of the get() function, and then declare all your variables are chars.
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    >> It doesn't matter since cin.get() returns an int and cout.put() takes a char,
    I missed that at first, but according to dinkumware's reference put takes a char and get has a version that works with char as well.

    >> you can get input using ">>" instead of the get() function
    The assignment requires get and put.

  5. #5
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    How on earth is anyone supposed to know that adding a space to an uppercase char makes if lowercase?
    There are functions for that sort of thing: isupper and tolower, iirc.

    Even if you insist on rolling your own, you should do:
    Code:
    lower = upper - 'A' + 'a';
    Which it may help to think of as:
    Code:
    lower = 'a' + (upper - 'A');
    That is of course after you've determined that it is even an alphabet character and not um say, a digit or punctuation mark etc.
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