poj3157

字符串处理

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
using namespace std;

string st;

int main()
{
    //freopen("t.txt", "r", stdin);
    cin >> st;
    bool java = false;
    bool cpp = false;
    if (st[0] == '_')
    {
        cout << "Error!" << endl;
        return 0;

    }
    for (int i = 0; i < st.length(); i++)
        if (st[i] >= 'A' && st[i] <= 'Z')
        {
            if (i == 0)
            {
                cout << "Error!" << endl;
                return 0;
            }
            java = true;
            break;
        }
    if (st.find('_') != string::npos)
        cpp = true;
    if (cpp && java)
    {
        cout << "Error!" << endl;
        return 0;
    }
    if (cpp)
    {
        if (st.find("__") != string::npos || st[st.length() - 1] == '_')
        {
            cout << "Error!" << endl;
            return 0;
        }
        for (int i = 0; i < st.length(); i++)
            if (st[i] == '_')
            {
                st.erase(i, 1);
                st[i] = st[i] - 'a' + 'A';
            }
    }
    else
    {
        for (int i = 0; i < st.length(); i++)
            if (st[i] >= 'A' && st[i] <= 'Z')
            {
                st[i] = st[i] - 'A' + 'a';
                st.insert(i, "_");
            }
    }
    cout << st << endl;
    return 0;
}