C#：while 与 if

Question

我只想接受州的两个大写字母缩写：AK、WA、OR、CA、AZ、NM、CO 或 UT。如果输入不是其中之一，则请求用户提供新的输入以进行更正。我下面的代码用于过滤结果，但是当我输入“UT”或“WA”时，它不会退出 while 循环并继续。

Write("State (We only ship to AK, WA, OR, CA, AZ, NM, CO, or UT):\t");
            stateName = Convert.ToString(ReadLine().ToUpper());
            while (!stateName.Contains("AK") || !stateName.Contains("WA") || !stateName.Contains("OR") 
                || !stateName.Contains("CA") || !stateName.Contains("AZ") || !stateName.Contains("NM") 
                || !stateName.Contains("CO") || !stateName.Contains("UT"))
            {
                Write("Error: We do not ship to {0}. We ONLY ship to AK, WA, OR, CA, AZ, NM, CO, or UT\t", stateName);
                stateName = Convert.ToString(ReadLine().ToUpper());
            }

进一步修改后，我得到了它：

Write("State (We only ship to AK, WA, OR, CA, AZ, NM, CO, or UT):\t");
            stateName = Convert.ToString(ReadLine().ToUpper());
            if (stateName != "AK" || stateName != "WA" || stateName != "OR"
                || stateName != "CA" || stateName != "AZ" || stateName != "NM"
                || stateName != "CO" || stateName != "UT")
            {
                Write("Error: We do not ship to {0}. We ONLY ship to AK, WA, OR, CA, AZ, NM, " +
                    "CO, or UT\t", stateName);
                stateName = Convert.ToString(ReadLine().ToUpper());
            }

我的问题是，如果逻辑非常相似，为什么 while 循环不起作用？ !variableName 与 variableName != value 不同吗？

Answer 1

问题出在你的逻辑上，你应该使用 And && 运算符而不是 Or ||:

while (
    !stateName.Contains("AK") && !stateName.Contains("WA") && !stateName.Contains("OR")
    && !stateName.Contains("CA") && !stateName.Contains("AZ") && !stateName.Contains("NM")
    && !stateName.Contains("CO") && !stateName.Contains("UT"))

我假设您正在学习，所以我使用了这段代码。在现实世界中，您应该使用数组来检查如此多的条件（您需要知道 for 循环和 Array）。

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