Question

How to invert the letters case in a String uppercase to lowercase and lowercase to uppercase in C#

Answer 1

using System;

namespace ConsoleApplication_C_Sharp
{
    class Program
    {
        static void Main(string[] args)
        {

            string s = "C Sharp Programming";

            s = InvertLettersCase(s);
            Console.WriteLine(s);

            Console.WriteLine(InvertLettersCase("Programming"));
        }

        static string InvertLettersCase(string s)
        {

            string rv = "";

            for (int i = 0; i < s.Length; i++)
            {
                if (Char.IsLower(s[i]))
                    rv += Char.ToUpper(s[i]);
                else if (Char.IsUpper(s[i]))
                    rv += Char.ToLower(s[i]);
                else
                    rv += s[i];
            }
            return rv;
        }
    }
}


/*
run:
    
c sHARP pROGRAMMING
pROGRAMMING

*/

 

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Answer 2

using System;

namespace ConsoleApplication_C_Sharp
{
    class Program
    {
        static void Main(string[] args)
        {

            string s = "C Sharp Programming";

            s = InvertLettersCase(s);
            Console.WriteLine(s);

            Console.WriteLine(InvertLettersCase("Programming"));
        }

        static char InvertCharCase(Char ch)
        {
            if (Char.IsLower(ch)) return Char.ToUpper(ch);
            if (Char.IsUpper(ch)) return Char.ToLower(ch);

            return ch;
        }

        static string InvertLettersCase(string s)
        {

            string rv = "";

            for (int i = 0; i < s.Length; i++)
                rv += InvertCharCase(s[i]);

            return rv;
        }
    }
}


/*
run:
    
c sHARP pROGRAMMING
pROGRAMMING

*/

 

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Answer 3

using System;
using System.Linq;

namespace ConsoleApplication_C_Sharp
{
    class Program
    {
        static void Main(string[] args)
        {

            string s = "C Sharp Programming";

            s = InvertLettersCase(s);
            Console.WriteLine(s);

            Console.WriteLine(InvertLettersCase("Programming"));
        }

        static string InvertLettersCase(string s)
        {
            return new string(s.Select(ch => char.IsLetter(ch) ? (char.IsUpper(ch) ?
                      char.ToLower(ch) : char.ToUpper(ch)) : ch).ToArray());
        }


    }
}


/*
run:
    
c sHARP pROGRAMMING
pROGRAMMING

*/

 

70+ SQL courses for beginners and professionals