不确定如何从我的输出中排除数值

Question

使用 C++ 我制作了这段代码来确定用户何时输入一个值，如果它是大写或小写值，或者根本不是一个值，那部分对我来说很容易，而且我还做了它，所以输出也会将小写输入转换为大写输入，将大写输入转换为小写输入我的 proffesort 只允许我们使用 if else 语句意味着没有数组或向量，如果它是数字值，我不确定如何将我的代码排除在转换之外我完全迷失在使用这个 ascii 表中。请帮忙下面是我的代码

#include <iostream>
using namespace std;
int main()
{
char Letter; //defines the char variable letter for the user to input a value

cout<< "Please input a letter :)!" << endl;
cin>> Letter;

    if ( Letter>= 65 && Letter <= 90) //checks the acsii dec values to see if the input is a
        cout<< "This is an uppercase letter!"<<endl;//lowercase letter
else  if (Letter >= 97 && Letter <= 122)//checks to see if the acsii dec value is 
          cout<< "This is a lower case letter!"<<endl;//uppercase
      else 
          cout<<"This is not a letter :("<<endl;//outputs this if the acsii value is not a letter

if (Letter >=65&& Letter <= 90)
{
    Letter+=32;
    cout<< Letter<<" "<<"This is the Lowercase of your uppercase letter!\n";
}
else  (Letter >= 97 && Letter <=122);
{
    Letter-=32;
    cout<< Letter<<" "<<"This is the Uppercase of your lowercase letter!\n";
}

system("pause");
return 0;

Answer 1

你的错误在这里：

else  (Letter >= 97 && Letter <=122);

我猜你想写：

else if (Letter >= 97 && Letter <=122);
    ^^^^

顺便说一句，如果只是重新排序代码以提高局部性，您可以使代码更小：

#include <iostream>
using namespace std;
int main()
{
  char Letter; //defines the char variable letter for the user to input a value

  cout<< "Please input a letter :)!" << endl;
  cin>> Letter;

  if ( Letter>= 65 && Letter <= 90) {
    cout<< "This is an uppercase letter!"<<endl;
    Letter+=32;
    cout<< Letter<<" "<<"This is the Lowercase of your uppercase letter!\n";
  } else  if (Letter >= 97 && Letter <= 122) {
    cout<< "This is a lower case letter!"<<endl;
    Letter-=32;
    cout<< Letter<<" "<<"This is the Uppercase of your lowercase letter!\n";
  } else 
    cout<<"This is not a letter :("<<endl;

   return 0;
}

Answer 2

到目前为止，您的代码仅适用于字母，如果用户输入不是字母，它不会做任何事情，我不明白您想从代码中排除什么？你的意思是说你想使用其他东西而不是 assci 值。

在这种情况下，您可以使用以下代码，这将避免您需要担心或记住 ascii 数字的完整 ASCII 值

 if ( Letter>= 'A' && Letter <= 'Z') //checks the acsii dec values to see if the input is a
    cout<< "This is an uppercase letter!"<<endl;//lowercase letter
else  if (Letter >= 'a' && Letter <= 'z')//checks to see if the acsii dec value is 
      cout<< "This is a lower case letter!"<<endl;//uppercase
  else 
      cout<<"This is not a letter :("<<endl;//outputs this if the acsii value is not a letter

 if (Letter >='A'&& Letter <= 'Z')
 {
   Letter+='a'-'A';
    cout<< Letter<<" "<<"This is the Lowercase of your uppercase letter!\n";
 }
 else  (Letter >= 'a' && Letter <='z');
 {
   Letter-='a'-'A';
   cout<< Letter<<" "<<"This is the Uppercase of your lowercase letter!\n";
  }