“无法启动程序” <目录>“系统找不到指定的文件”

Question

我找不到我的错误

#include <iostream>

using namespace std;

string versionn(int, toool);

int main(){

    cout << versionn(3);
}

string versionn(int, toool) {
    string vername;

    switch (toool) {

    case 0:
        vername = "version 1";
        break;
    case 1:
        vername = "version 2";
        break;
    case 2:
        vername = "version 3";
        break;
    case 3:
        vername = "version 4";
        break;
    default:
        vername = "5";

    }

    return vername;
}