Variable declarations following if statements

problem ：

An issue came up on another forum and I knew how to fix it, but it revealed a feature of the compiler peculiar to me. There is a problem in another forum , I know how to solve it , But it reveals my unique compiler features .The person was getting the error "Embedded statement cannot be a declaration or labeled statement" because they had a declaration of a variable following an if statement with no brackets. This person received an error message “ Embedded statements cannot be declarative or tagged statements ”, Because they're if There is an parenthesized variable declaration after the statement .That was not their intent, but they had commented out the line of code immediately following the if statement, which made the variable declaration the de facto line of code to execute. This is not their intention , But they are if The code line is commented out immediately after the statement , This makes the variable declaration the line of code to actually execute .Anyway, that's the background, which brings me to this. in any case , This is the background , This reminds me of this .

The following code is illegal The following code is illegal

if (true)    int i = 7;

However, if you wrap that in brackets, it's all legal. however , If you put it in square brackets , Is completely legal .

if (true){    int i = 7;}

Neither piece of code is useful. These two pieces of code are useless .Yet the second one is OK. The second one is ok .What specifically is the explanation for this behavior? What is the specific explanation for this behavior ？

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Solution ：

Reference resources ： https://stackoom.com/en/question/ATTZ