对于循环函数参数错误

Question

    void Image::setValues(int start_row, int end_row, int start_column, int end_column, Image & source)
{
    int startPosX = start_row;
    int startPosY = start_column;

    for (int row = 0; startPosX < end_row; row++, startPosX++)
        for (int col = 0; startPosY < end_column; col++, startPosY++)
            std::cout << startPosX << "  " << startPosY << std::endl;
}

我将此功能称为

imageTest.setValues(0, 32, 0, 32, imageTest2);

我希望输出1024组数字（32 * 32）而不是输出如下所示。

我做错了什么？

Answer 1

您忘记在内循环开始时初始化startPosY。

试试这个：

void Image::setValues(int start_row, int end_row, int start_column, int end_column, Image & source)
{
    int startPosX = start_row;
    int startPosY = start_column;

   for (int row = 0; startPosX < end_row; row++, startPosX++) {
        startPosY = start_column;
        for (int col = 0; startPosY < end_column; col++, startPosY++)
            std::cout << startPosX << "  " << startPosY << std::endl;
    }
}

Answer 2

除了使逻辑变得更复杂并导致你犯错误之外，

startPosX和startPosY没有做任何有用的事情。

没有它们会更简单，更清晰：

for (int row = start_row; row < end_row; row++)
    for (int col = start_column; col < end_column; col++)
        std::cout << row << "  " << col << std::endl;