How to judge Interact problem

[Worldcpu]

最近我在做函数式交互题的时候发现 cph-ng 是具有交互题功能，但是我设置了之后发现会出现collect2报错找不到 main 函数，请问 CPH-NG 是只支持 IO 交互吗，未来会添加函数式交互的支持吗？或者是我的使用问题？

[Worldcpu]

Recently, while working on function-style interactive problems, I noticed that cph-ng has interactive problem support. However, after setting it in the problem's page, I encountered a compiler error from collect2 saying it couldn’t find the main function.

So I’d like to ask: does cph-ng only support I/O-style interactive problems? Will function-style interactive support be added in the future, or is this an issue with my usage?

/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/13/../../../x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x1b): undefined reference to `main'
collect2: error: ld returned 1 exit status

[langningchen]

We use testlib for standard I/O interaction. For function interaction, you can try to #include "grader.cpp".

Click to expand the example of I/O interaction

// source.cpp
#include <bits/stdc++.h>
using namespace std;
int main()
{
    int l = 1, r = 1000000000;
    while (true)
    {
        int mid = l + (r - l) / 2;
        cout << mid << endl;
        cout.flush();
        int res;
        cin >> res;
        if (res == 0)
            break;
        else if (res == -1)
            l = mid + 1;
        else
            r = mid - 1;
    }
    return 0;
}

// spj.cpp
#include "testlib.h"
using namespace std;
int main(int argc, char **argv)
{
    registerInteraction(argc, argv);
    int n = inf.readInt();
    cout.flush();
    int left = 50;
    bool found = false;
    while (left > 0 && !found)
    {
        left--;
        int a = ouf.readInt(1, 1000000000);
        if (a < n)
            cout << -1 << endl;
        else if (a > n)
            cout << 1 << endl;
        else
            cout << 0 << endl, found = true;
        cout.flush();
    }
    if (!found)
        quitf(_wa, "couldn't guess the number with 50 questions");
    ouf.seekEoln();
    ouf.readEof();
    quitf(_ok, "guessed the number with %d questions!", 50 - left);
}