c++ - for循环中的条件不执行

Question

我正在编写一个简单的程序，使棋盘上每个方格的米粒数量增加一倍。我正在尝试计算至少 1 000 000 000 粒大米所需的正方形数量。问题是，无论我尝试什么，第二个 if 语句都会被跳过，即使在第一次迭代后“test”为 false。

我在 if 语句之后尝试了 else，但是当“test”变量为 false 时跳过了 else。

    constexpr int max_rice_amount = 1000000000;  
    int num_of_squares = 0;
    int rice_grains = 0;
    bool test = true; // so we can set rice_grains amount to 1

    for (int i = 0; i <= max_rice_amount; i++)
    {
        if (test == true)
        {
            rice_grains = 1;  // This will only happen once
            test = false;
        }
        else if (test == false)
            rice_grains *= 2;

        ++num_of_squares;
        std::cout << "Square " << num_of_squares << " has " << rice_grains << " grains of rice\n";

    }

Answer 1

else 导致了问题。但是C++比你想象的更强大。将循环重做为

for (
    int rice_grains = 1, num_of_squares = 1;
    rice_grains <= max_rice_amount;
    rice_grains *= 2, ++num_of_squares
){

与

 std::cout << "Square " << num_of_squares << " has " << rice_grains << " grains of rice\n";

作为循环体；为美丽而哭泣。