Checking equality for Characters

[decastroenzo]

I need to check whether a variable is equal to a character. is that okay?

 //Modify the previous program such that only the users Alice and Bob are greeted with their names.

#include <iostream>
#include <string>

using namespace std;
int main()
{
	string x;

	cout<<"Hello! Please enter your name.\n\n";
	cin>>x;

	if (x=="Alice" or x=="Bob")
	{
		cout<<"Hello there, "<<x;
	}
	else
	{
		cout<<"sorry don't know you haha";
	}
	system("pause");
	return 0;

}

halp

[bird1234]

use this || for or operator yes you can do that

[boost lexical cast]

bird1234 that was not helpful.

OP, this works:

#include <iostream>
#include <string>

int main()
{
    std::string str;

    std::cout << "Enter a character: " << std::flush;
    while (!(std::cin >> str) || str.length() != 1)
    {
        std::cin.clear();
        std::cin.ignore();
        std::cout << "Invalid. Re-enter: " << std::flush;
    }

    std::cout << "You " << (str == "a" ? "entered" : "didn't enter") << " \'a\'\n";

    return 0;
}

[Peter87]

The original code works fine but requires the user to input the name with that exact capitalization. "bob", "BOB" or "bOb" will give the "sorry don't know you" response. To make the comparison case-insensitive you could loop through the string and turn every character into lower case using std::tolower, and then compare the string to the lower case "bob".

void convertToLowerCase(std::string& str)
{
	for (char& c : str)
	{
		c = std::tolower(c);
	}
}

// in main
convertToLowerCase(x);
if (x == "alice" || x == "bob")
{

Another way is to write a comparison function that loops through both strings and call std::tolower on each pair of character before comparing them.

bool isEqualCaseInsensitive(const std::string& str1, const std::string& str2)
{
	if (str1.length() != str2.length())
	{
		return false;
	}
	
	for (std::size_t i = 0; i < str1.length(); ++i)
	{
		if (std::tolower(str1[i]) != std::tolower(str2[i]))
		{
			return false;
		}
	}
	return true;
}

// in main
if (isEqualCaseInsensitive(x, "Alice") ||
    isEqualCaseInsensitive(x, "Bob"))
{

[decastroenzo]

I appreciate the help! but I can't understand :(

[Natako]

#include <iostream>
#include <string>
#include <cctype>

using namespace std;

string toLowerString(string s) 
{
    int i;
    for(i = 0; i < s.size(); i++) s[i] = tolower(s[i]);
    return s;
}

int main()
{
	string x;

	cout << "Hello! Please enter your name : ";
	cin >> x;

	if (toLowerString(x) == "alice" || toLowerString(x) == "bob")
	{
		cout << "Hello there, " << x << endl;
	}
	else
	{
		cout << "Sorry don't know you haha" << endl;
	}

	system("pause");
	return 0;
}

[48T7M4Gy]

#include <iostream>
#include <string>

using namespace std;
int main()
{
    string x;
    char y = ' ';
    
    cout<<"Hello! Please enter your name.\n\n";
    cin>>x;
    
    if (x=="Alice" or x=="Bob")
    {
        cout<<"Hello there, "<<x << '\n';
    }
    else
    {
        cout<<"sorry don't know you haha\n";
    }
    
    cout<<"Hello! Please enter your first initial.\n\n";
    cin >> y;
    
    // NOT CASE SENSITIVE - ONE WAY THE HARD WAY
    if (y == 'A' or y == 'a')
        cout<<"Hello there, "<< y << '\n';
    else
        cout<<"sorry don't know you haha\n";
    
    // NOT CASE SENSITIVE - BETTER WAY
    if(tolower(y) == 'a')
        cout<<"Hello there, "<< y << '\n';
    else
        cout<<"sorry don't know you haha\n";
    
    
    
    system("pause");
    return 0;
    
}

[E0p9LyTq]

#include <iostream>
#include <string>
#include <cctype>

int main()
{
   std::string name;

   std::cout <<"Hello! Please enter your name: ";
   std:: cin >> name;

   std::cout << "\n";

   for (auto& str_loop: name)
   {
      str_loop = toupper(str_loop);
   }

   if (name == "ALICE" || name == "BOB")
   {
      std::cout << "Hello there, " << name << "\n";
   }
   else
   {
      std::cout << "I don't know you...haha\n";
   }
}

Hello! Please enter your name: bob

Hello there, BOB

Hello! Please enter your name: Tom

I don't know you...haha

[Natako]

@FurryGuy
Your example does not preserve the original input the user has entered.
Better create a temporary variable to do the comparison.

[E0p9LyTq]

@Natako, if you think that is required, then by all means make it so. I don't see any requirement in the OP post that prevents altering the input.