Okay, so I'm basically trying to create a C++ program that determines the case of the letter. The program will basically ask for a letter input, uppercase or lowercase and then the program will say whether that letter the user inputted is an uppercase or a lowercase letter. Help is advised. Thank you.


Input:

#include <iostream>
using namespace std;

int main()
{
    char ch;
    cout << "Enter any character, lowercase or uppercase: ";
    cin >> ch;
    
    if ('A' != 'z')
    cout << "The character just entered is a lowercase letter." << endl;
    else if('a' != 'Z')
    cout << "The characer just entered is not a lowercase letter." << endl;
    else
    cout << "An invalid character was entered." << endl;
    
    system ("PAUSE");
    
    return EXIT_SUCCESS;
    return 0;
}

Output: LOWERCASE WORKS FINE
Enter any character, lowercase or uppercase: a
The character just entered is a lowercase letter.
Press any key to continue . . .

Output: UPPERCASE DOESN'T WORK
Enter any character, lowercase or uppercase: A
The character just entered is a lowercase letter.
Press any key to continue . . .


_______________________________________________
If I switch

if ('A' != 'z')

To instead of (!=) to (<), the program will flip over saying this.

Output: LOWERCASE DOESN'T WORK
Enter any character, lowercase or uppercase: a
The character just entered is not a lowercase letter.
Press any key to continue . . .

Output: UPPERCASE WORKS FINE
Enter any character, lowercase or uppercase: A
The character just entered is not a lowercase letter.
Press any key to continue . . .
_______________________________________________________
The exact same results appear if I switch this

else if('a' != 'Z')

Thank you for helping. I'm just a beginner in C++

I think that you have mis-understood what is going on in your if statements.

The condition if ('A' != 'z') is ALWAYS true for the standard ASCII character set. It is the same as writing if (65 != 122) which you can see is ALWAYS true.

Ok so what do you need to do. You need to test a range. Lets us first consider an integer value e.g.

int x=28;
if (x>10 && x<30)
  std::cout<<"X is between 10 and 30"<<std::endl;

As you can see I have two conditional tests combined with a boolean operator.
The if line first tests x>10 and then x<30 and combines them with an operator.

[NOTE: in C++ the compiler guarantees that it will test the first test first, and
that if it finds that the result is true/false without needing the remainder of the tests then it does not carry out those tests]

The && operator combines to results using the AND boolean operator.

For your test you can do this: if (ch>='a' && ch<='z') which tests to see if ch is between the ascii values of a and z.
Note that I have used a >= operator since obviously 'a' is a lower case value as is
'z'.

You could also use islower(ch) which is slightly better style because it deals with international character sets etc.

From here we have an example of the "correct" way to handle locale facets, including upper and lower.

// ctype::is example
#include <iostream>
#include <locale>
using namespace std;

int main ()
{
  locale loc;
  char quote[] = "It is wonderful how much may be done if we are always doing.";
               // (Attributed to Thomas Jefferson)
  int length = sizeof(quote);
  ctype<char>::mask * masks = new ctype<char>::mask [length];

  cout << '"' << quote << '"' << endl;

  cout << "The quote begins with an uppercase letter? ";
  bool upper = use_facet< ctype<char> >(loc).is( ctype<char>::upper, quote[0]);
  cout << boolalpha << upper << endl;

  int cx = 0;
  use_facet< ctype<char> >(loc).is (quote, quote+length, masks);
  for (int i=0; i<length; ++i) if (masks[i] & ctype<char>::space) ++cx;
  cout << "The quote has " << cx << " whitespaces.\n";
  return 0;
}
// output
// "It is wonderful how much may be done if we are always doing."
// The quote begins with an uppercase letter? true
// The quote has 12 whitespaces.
Comments
True, but take the OP's experience into account. He wouldn't know what to do with this code.
How it should be done
Nice example. Thx.

Hey

For this problem i have devised a simple solution that i think meets your needs please consider the following.

#include <iostream>
#include <cctype>>

using namespace std;

int main()
{
    char ch;
    char compare;
    
    cout << "Enter any character, lowercase or uppercase: ";
    ch = cin.get();
    
    if(isalpha(ch))//check the character is a character not a number or escape sequence etc
    {
		compare  = toupper(ch);//convert ch to upperacse and store in compare (ch unchanged)
		if(compare==ch)//the original is upperace
		{
			cout<<"UpperCase character entered"<<endl;
		}
		else//character is lower case
		{
			cout<<"LowerCase character entered"<<endl;
		}
	}
	else
	{
		cout<<"Invalid Input "<<ch<<" is not a character"<<endl;
	}



    system ("PAUSE");

    return EXIT_SUCCESS;
    return 0;
}

Hope this helps, any questions about how my solution works if you cant see how it is working please post a reply or feel free to pm me.

This article has been dead for over six months. Start a new discussion instead.