尝试在C#控制台应用程序中使用ToUp和ToDown验证用户定义的字符串是否在字典中，其中包含字符串和int元素，然后用ConstainsKey打印出元素。例如（简体）：

Dictionary<string, int> example = new Dictionary<string, int>();

//int for number of each type of element
int elements = 3;

for (int i = 0; i < elements; i++)
{
     Console.WriteLine("What is the key?");
     string stringElement = Console.ReadLine();
     
     //Validation loop
     while (string.IsNullOrWhileSpace(stringElement))
     {
          Console.WriteLine("error");
          Console.WriteLine("What is the key?");
          stringElement = Console.ReadLine();
     }
     //Ask user for value
     Console.WriteLine("What is the value?");

     string numElementString = Console.ReadLine();

     while (string.IsNullOrWhiteSpace(intElementString) || (!(int.TryParse(numElementString, out numElement))) || numElement <= 0)
     {
          Console.WriteLine("error");
          Console.WriteLine("What is the value?");
          numElementString = Console.ReadLine();
     }
     example.Add(stringElement, numElement);
}

//What does user want to have printed
Console.WriteLine("What elements are you looking for? Please type in the key you need.");

//Catch key user answers
string userAnswer = Console.ReadLine();

//userAnswer validation look for IsNullOrWhiteSpace
while (string.IsNullOrWhiteSpace(userAnswer))
{
     Console.WriteLine("error");
     Console.WriteLine("What elements are you looking for? Please type in the key you need.");
     userAnswer = Console.ReadLine();

到目前为止，我只是在使用ToUp和Tolower表达式让控制台打印出特定的时遇到了问题