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C语言指针最多有多少级？

 3 years ago
source link: https://www.zhihu.com/question/448862096/answer/1785538661
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C语言指针最多有多少级？ - 知乎
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没有限制。另外题主写100级指针不需要写100个星号，还容易出错。

template<typename T>
using AddPointer = T*;

template<typename T, size_t Depth>
struct DepthPointer:
    DepthPointer<AddPointer<T>, Depth - 1> { };

template<typename T>
struct DepthPointer<T, 0> {
    using type = T;
};

DepthPointer<int, 100>::type p100{};

怎么知道p100的类型？dump出来看看。

$ clang -Xclang -ast-dump -fsyntax-only test.cpp
`-FunctionDecl 0x226d460 <line:29:1, line:31:1> line:29:5 main 'int ()'
  `-CompoundStmt 0x22b0670 <col:12, line:31:1>
    `-DeclStmt 0x22b0658 <line:30:5, col:40>
      `-VarDecl 0x22b0570 <col:5, col:39> col:34 p100 'DepthPointer<int, 100>::type':'int ****************************************************************************************************' listinit
        `-InitListExpr 0x22b0618 <col:38, col:39> 'DepthPointer<int, 100>::type':'int ****************************************************************************************************'

确实是100级指针：'DepthPointer<int, 100>::type':'int ****************************************************************************************************'

另外这个超过1024级指针clang编译器会因为爆栈而挂掉，而gcc没有这个限制，想要多少级要多少级。测试的时候记得编译选项加上-ftemplate-depth=999999 。


report

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