这个 if 语句会导致不好的事情发生吗？

发布于 2024-09-06 11:24:55 字数 345 浏览 2 评论 0原文

int expenseCode;
if (int.TryParse(sourceRecord.ExpenseCode, out expenseCode) && _ExpenseCodeLookup.ContainsKey(expenseCode))
{
     destRow.PROFIT_CENTER_NAME = _ExpenseCodeLookup[expenseCode];
}
else
     destRow.PROFIT_CENTER_NAME = "Unknown";

我担心的是第一个表达式是否总是在第二个操作之前运行（在进程中设置expenseCode）？

原文

int expenseCode;
if (int.TryParse(sourceRecord.ExpenseCode, out expenseCode) && _ExpenseCodeLookup.ContainsKey(expenseCode))
{
     destRow.PROFIT_CENTER_NAME = _ExpenseCodeLookup[expenseCode];
}
else
     destRow.PROFIT_CENTER_NAME = "Unknown";

The thing I am conerned about is will the first expression always be run (setting expenseCode in the process) before the second operation?

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不爱素颜 2024-09-13 11:24:55

没关系。 && 在 C# 中是短路的，out 参数在 之前肯定已经被 TryParse 分配了合适的值调用 ContainsKey。

另一方面，您可以再次使用相同的技巧来获取值：

string profitCenter;
int expenseCode;
if (int.TryParse(sourceRecord.ExpenseCode, out expenseCode) && 
    _ExpenseCodeLookup.TryGetValue(expenseCode, out profitCenter))
{
    destRow.PROFIT_CENTER_NAME = profitCenter;
}
else
{
    destRow.PROFIT_CENTER_NAME = "Unknown";
}

这样您只需查找费用代码一次。

That's fine. && is short-circuiting in C#, and the out parameter will definitely have been assigned the appropriate value by TryParse before ContainsKey is called.

On the other hand, you could use the same trick again to fetch the value:

string profitCenter;
int expenseCode;
if (int.TryParse(sourceRecord.ExpenseCode, out expenseCode) && 
    _ExpenseCodeLookup.TryGetValue(expenseCode, out profitCenter))
{
    destRow.PROFIT_CENTER_NAME = profitCenter;
}
else
{
    destRow.PROFIT_CENTER_NAME = "Unknown";
}

This way you're only doing the lookup of the expense code once.

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