检查整数是否太大 [英] Check if Integer is too great

问题描述

我正在研究交易系统，用户正在设定交易所的价格和金额。

I am working on an exchange system and the user is setting the price and amount for an exchange.

我想确保交易所不超过整数最大值，但我遇到了问题。

I want to make sure that the exchange is no greater than the Integer maximum value, but I am running into a problem.

当交换金额达到9或更多时，即使我有一个检查以确保数字不大于最大值，它不起作用。我做了一些调试，当设置金额为9而价格为2,147,483,646（比最大数量少1）时，打印出来：

When the amount of the exchange is put to 9 or more, even though I have a check to make sure the number is no greater than the maximum value, it does not work. I have done some debugging and when setting the amount to 9 while the price is 2,147,483,646 (1 less than the max number), it prints out this:

2,147,483,630 - 9

2,147,483,630 - 9

这是我的调试代码，我应该添加什么来确保不会发生这种情况？

This is my debugging code, what should I add to it to make sure that this does not happen?

public void setPrimaryAmount(int primaryAmount) {
        int price = primaryAmount * this.price;
        System.out.println(Misc.format(this.price * primaryAmount) + " - " + primaryAmount);
        if (price > Integer.MAX_VALUE ||
                price == Integer.MAX_VALUE ||
                price >= Integer.MAX_VALUE ||
                price < 0 || price <= 0 ||
                price++ == Integer.MAX_VALUE) {
            System.out.println("Attempted to set a bad amount.");
            return;
        }
        this.primaryAmount = primaryAmount;
    }

尝试设置不良金额打印出来，直到您输入金额> = 9。

"Attempted to set a bad amount" prints out until you enter an amount >= 9.

推荐答案

您无法在int中存储值，然后检查到看看它对于int来说是否太大了。把它存放在一个很长的位置。

You can't store a value in an int, and then check to see whether it's too big for an int. Store it in a long instead.

long price = (long)primaryAmount * (long)this.price;

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