C++ 为什么我在 for 循环中收到“Else without previous if”错误？
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Why am I getting an 'Else without previous if' error within a for loop?
提问by stringgy
I'm new to C++ and have been staring at my (probably abysmal) code for a while and can't figure out what's off about it.
我是 C++ 的新手，并且一直盯着我的（可能是糟糕的）代码一段时间，但无法弄清楚它有什么问题。
I'm trying to loop through a few iterations of if and else statements and must be doing something grammatically incorrect - as it shows compiler errors of 'else without a previous if'
我正在尝试遍历 if 和 else 语句的几次迭代，并且必须做一些语法错误的事情 - 因为它显示了“else without a previous if”的编译器错误
This is for a class and I'm trying to work it out, but if you see something obvious that I am overlooking I would love to know.
这是一个班级，我正在努力解决它，但是如果您看到我忽略的明显内容，我很想知道。
Thank you!
谢谢！
for (i = 0; i < iterationsNum; i++){
if (charlieAlive == 0) // Aarron's shot
{
if (aaronShot() == 1)
charlieAlive = 1;
}
else (charlieAlive == 1 && bobAlive == 0);{
if (aaronShot() == 1)
bobAlive = 1;
}
else (charlieAlive == 1 && bobAlive == 1 && aaronAlive == 0);{
cout << "Aaron is the Winner!\n";
totalShot++;
aaronCounter++;
}
continue;
if (charlieAlive == 0 && aaronAlive ==0) // Bob's shot
{
if (bobShot() == 1)
charlieAlive = 1;
}
else (charlieAlive == 1 && aaronAlive == 0);{
if (bobShot() == 1)
aaronAlive = 1;
}
else (charlieAlive == 1 && aaronAlive == 1 && bobAlive == 0);{
cout << "Bob is the Winner!\n";
bobCounter++;
totalShot++;
}
continue;
if (charlieAlive == 0 && bobAlive == 0) // Charlie's shot
{
bobAlive = 1;
}
else (charlieAlive == 0 && bobAlive == 1 && aaronAlive == 0);{
aaronAlive = 1;
totalShot++;
}
else (charlieAlive == 0 && bobAlive == 1 && aaronAlive == 1);{
cout << "Charlie is the Winner!\n";
}
continue;
回答by Nawaz
elsedoesn' take any condition, but you've written this:
else不带任何条件，但你已经写了这个：
else (charlieAlive == 1 && bobAlive == 0); //else : (notice semicolon)
which doesn't do what you intend it to do.
这不会做你打算做的事情。
You want to do thos:
你想这样做：
else if (charlieAlive == 1 && bobAlive == 0) //else if : (semicolon removed)
Notice the difference.
注意区别。
Also, there can be at most one elseblock, associated with an ifblock Or a chain of if, else-if, else-ifblocks. That is, you can write this:
此外，最多可以有一个else区块，与一个if区块或一系列区块相关联if, else-if, else-if。也就是说，你可以这样写：
if (condition) {}
else {}
Or,
或者，
if (condition0) {}
else if (condition1) {}
else if (condition2) {}
else if (condition3) {}
else if (condition4) {}
else {}
In any case, elseblock is alwaysthe last block. After that if you write another elseblock, that would be an error.
在任何情况下，else块始终是最后一个块。之后，如果您编写另一个else块，那将是一个错误。
Apart from that you also have a semicolon at wrong place. Fixed that also:
除此之外，您在错误的位置也有一个分号。还修复了：
else (charlieAlive == 1 && bobAlive == 0); <---- remove this semicolon!
Hope that helps.
希望有帮助。
Pick a good Introductory C++ Book. Here are few recommendations for all levels.
选择一本好的 C++ 入门书籍。以下是针对所有级别的一些建议。
回答by Krease
There are several problems I see here:
我在这里看到了几个问题：
- There are semicolons in your else statements - these aren't supposed to be there
- You have multiple else clauses for a single if. Use 'else if' when you are evaluating another condition - else is the catch-all for when no conditions are met
- I highly recommend proper indenting and consistent brace usage - not doing this isn't necessarily an error, but it will make it much easier to notice errors.
- 您的 else 语句中有分号 - 这些不应该在那里
- 单个 if 有多个 else 子句。在评估另一个条件时使用“else if” - else 是不满足任何条件时的包罗万象
- 我强烈推荐适当的缩进和一致的大括号使用 - 不这样做不一定是错误，但它会更容易发现错误。
回答by exexzian
you cant put condition statement in elsestatement
你不能把条件语句放在else语句中
correct for all elsestatements
对所有其他语句都是正确的
like in else (charlieAlive == 1 && bobAlive == 0);
像 else (charlieAlive == 1 && bobAlive == 0);
elseis simply the alternative flow of if- i.e.
else只是替代流程if- 即
if(condition) // if this fails go to else part
{
--- // if condition true execute this
}
else{
--- // will run when condition in if fails
}
so you don't have to put condition for else statement
所以你不必为 else 语句设置条件
Edit
where as else iftakes condition as well
seems you wanted to do thiselse if(your condition statements)// Note: no semicolon at the end
编辑
where aselse if需要条件似乎你想这样做else if(your condition statements)// 注意：最后没有分号
