三种写法：

#include <cstring>

using namespace std;

int main()
{
    string a,b;
    getline(cin,a);
    getline(cin,b);

    for (int i = 0; i < a.size(); i ++)
        if (a[i] >= 'A' && a[i] <= 'Z') a[i] += 32;

    for (int i = 0; i < b.size(); i ++)
        if (b[i] >= 'A' && b[i] <= 'Z') b[i] += 32;

    int c;
    c = strcmp(a.c_str(),b.c_str()); //!!!!
    if(c < 0) cout << "<";
    if(c == 0) cout << "=";
    if(c > 0) cout << ">";

    return 0;
}

#include<iostream>
using namespace std;
int main()
{
    string a,b;
    getline(cin,a);
    getline(cin,b);
    for(auto &c:a) c = tolower(c);  //!!!
    for(auto &c:b) c = tolower(c);
    if(a == b) cout << '=';         //!!!
    if(a > b) cout << '>';
    if(a < b) cout << '<';
}

#include <iostream>
using namespace std;

int main()
{
    string a, b;
    getline(cin, a);
    getline(cin, b);
    int t = 0;
    // int m = a.size()>b.size() ? a.size():b.size();
    int m = max(a.size(), b.size());                   //!!!!
    for(int i = 0; i < m; i++)
    {   
        if(a[i] >= 'a' && a[i] <= 'z') a[i] -= 32;     //!!!!
        if(b[i] >= 'a' && b[i] <= 'z') b[i] -= 32;
        if(a[i] == b[i])
            t++;
        else if(a[i] > b[i])
        {
            cout << ">" << endl;
            break;
        }
        else if(a[i] < b[i])
        {
            cout << "<" << endl;
            break;
        }
    }
    if(t == m) cout << "=" << endl;               // !!!!!
    return 0;
}