c - 左操作数必须是左值

Question

有人可以帮忙吗？这两行代码出错。 num_red - count_red = red_pot;// all defined as 0 和

while (count_red = 0 && count_yellow = 0 && count_green = 0 && count_brown = 0 && count_blue = 0 && count_pink = 0)
        {
            if (count_black = 0)
            {
                score = score + 7;
                printf("Score: %d\n", score);
                num_balls = num_balls - 1;
            }

        }

Answer 1

如果那是一种类似 C 的语言，则需要==用于相等检查，而不是=. 单曲=用于分配，以便：

int seven = 7;
int five = 5;
if (seven - five == 2) ...

没关系，但是：

int seven = 7;
int five = 5;
if (seven - five = 2) ...

即使它编译，也不会做你所期望的。

您的代码中有一个经典示例。细分：

if (count_black = 0) blah;

为零时不会执行blah。count_black它将设置 count_black为零并坚决拒绝执行blah，因为结果count_blah = 0为 0（假）。

---

如果你想要平等：

num_red - count_red == red_pot

to be true, you need to assign one of those variables (the "unknown" one) based on the other two "known" ones. For example, if num_red and count_red are known, set red_pot with:

red_pot = num_red - count_red;

Alternatively, if red_pot and count_red are known, set num_red with:

num_red = count_red + red_pot;