而大写和小写字母输入功能

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <iomanip>
#include <string>
#include <time.h>
#include <unistd.h>
#include <dos.h>
#include <windows.h>
#include <chrono>
#include <thread>
using namespace std;
using namespace std::this_thread; // sleep_for, sleep_until
using namespace std::chrono; // nanoseconds, system_clock, seconds
int main()
{
string word = "A";
do
{
system("CLS");
system("COLOR 3");
cout<<"nH";
usleep(50000);
cout<<"I ";
usleep(50000);
cout<<"T";
usleep(50000);
cout<<"H";
usleep(50000);
cout<<"E";
usleep(50000);
cout<<"R";
usleep(50000);
cout<<"E "<<endl<<endl;
sleep_for(seconds(1));
cout<<"H";
usleep(50000);
cout<<"O";
usleep(50000);
cout<<"W ";
usleep(50000);
cout<<"A";
usleep(50000);
cout<<"R";
usleep(50000);
cout<<"E ";
usleep(50000);
cout<<"Y";
usleep(50000);
cout<<"O";
usleep(50000);
cout<<"U? "<<endl<<endl;
usleep(50000);
sleep_for(seconds(1));
cout<<"H";
usleep(50000);
cout<<"O";
usleep(50000);
cout<<"P";
usleep(50000);
cout<<"E ";
usleep(50000);
cout<<"Y";
usleep(50000);
cout<<"O";
usleep(50000);
cout<<"U";
usleep(50000);
cout<<"'R";
usleep(50000);
cout<<"E ";
usleep(50000);
cout<<"D";
usleep(50000);
cout<<"O";
usleep(50000);
cout<<"I";
usleep(50000);
cout<<"N";
usleep(50000);
cout<<"G ";
usleep(50000);
cout<<"G";
usleep(50000);
cout<<"R";
usleep(50000);
cout<<"E";
usleep(50000);
cout<<"A";
usleep(50000);
cout<<"T"<<endl<<endl;
usleep(50000);
cout<<"A.Im doing great :)       B.Im sad :/"<<endl;
cin>>word;
}
while(word!="A"||word!="a"); //I want to let input be upper/lower case
cout<<"this means its A and going for next command"<<endl;
return 0;
}

你好，所以基本上我是大学的新生，学习计算机科学课程，我正在尝试自己学习(比其他人领先一步(

在这个程序中，我的目标是制作一个响应式机器：具有 2 个或更多答案选项的问题，如果答案不在上下文中，则使用系统("CLS"(，然后重复问题(循环(。装饰："系统颜色"表示颜色，"usleep"表示单词中的字母动画，"sleep_for"表示单词行之间的间隙

1.如何修复 while 命令，它无法检测到我是否同时放置了两个条件 "while(word！="A"||单词！="a"(;" 2.如果有更简单的方法来逐个字母地表达单词，请告诉。