C++ ostream 参数

Question

我正在构建一个解决boggle board的项目。 我目前感兴趣的两个功能是

void Boggle::SolveBoardHelper(bool printBoard, int row, int column, int rowMax, int columnMax,
                              ofstream& output, int numSteps, int steps[4][4], string currPath)


void Boggle::SolveBoard(bool printBoard, ostream &output) {
    ofstream outputFile;
    outputFile(output); // stuck here
    string currPath; // used to track the current path on the board

    for(int pos_x = 0; pos_x < BOARD_SIZE; pos_x++){
        for(int pos_y = 0; pos_y < BOARD_SIZE; pos_y++)
            SolveBoardHelper(print_or_not, pos_x, pos_y, BOARD_SIZE, BOARD_SIZE, outputFile, numSteps, visited, currPath);
    }  

}

我的困惑之处在于，当用户调用 SolveBoard 来求解棋盘时，他们可以选择将“cout”或输出文件传递到 ostream 参数中。 如果用户决定调用该函数并传入一个输出文件，比如“output.txt”，我该如何解释？ 我如何获取用户传递给 SolveBoard 参数的输出文件，然后将其插入到 SolveBoardHelper 函数中，以便在解决板后写入该文件？

我之前的尝试包括我只是将一个预定的输出文件传递到参数中，但我不知道用户会选择输出到哪个文件：

void Boggle::SolveBoard(bool printBoard, ostream &output) {
   
    string outputFile = "solve_output_test.txt"; // write to the already created solve_output_test.txt file
    ofstream outFile(outputFile); // assign it to ofstream variable outFile
    if(!outFile){
        cout << "Error opening file" << endl; // file open check
    }
    string currPath; 
    
    for(int pos_x = 0; pos_x < BOARD_SIZE; pos_x++){
        for(int pos_y = 0; pos_y < BOARD_SIZE; pos_y++) 
            SolveBoardHelper(print_or_not, pos_x, pos_y, BOARD_SIZE, BOARD_SIZE, outFile, numSteps, visited, currPath);
    }   
}

Answer 1

void Boggle::SolveBoard(bool printBoard, ostream &output) {
    // remove the two lines below and just use `output` in the rest of the function:
    //ofstream outputFile; 
    //outputFile(output);
    
    for(int pos_x = 0; pos_x < BOARD_SIZE; pos_x++) {
        for(int pos_y = 0; pos_y < BOARD_SIZE; pos_y++)
            SolveBoardHelper(print_or_not, pos_x, pos_y, BOARD_SIZE, BOARD_SIZE, output,
                             numSteps, visited, currPath);
    }  
}

然后调用函数

SolveBoard(the_bool, std::cout);

或者

std::ofstream file("output.txt");
SolveBoard(the_bool, file);

您还需要重新定义SolveBoardHelper以采用ostream ：

void Boggle::SolveBoardHelper(bool printBoard, int row, int column, int rowMax,
                              int columnMax, ostream& output, int numSteps,
                              int steps[4][4], string currPath)