user-0 提问: C语言的double pointer的类型转换问题

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user: user-1
content: //C++ Operators //  Operators specify an evaluation to be performed on one of the following: //    One operand (unary operator) //    Two operands (binary operator) //    Three operands (ternary operator) //  The C++ language includes all C operators and adds several new operators. //  Table 1.1 lists the operators available in Microsoft C++. //  Operators follow a strict precedence which defines the evaluation order of //expressions containing these operators.  Operators associate with either the //expression on their left or the expression on their right;    this is called //“associativity.” Operators in the same group have equal precedence and are //evaluated left to right in an expression unless explicitly forced by a pair of //parentheses, ( ). //  Table 1.1 shows the precedence and associativity of C++ operators //  (from highest to lowest precedence). // //Table 1.1   C++ Operator Precedence and Associativity // The highest precedence level is at the top of the table. //+------------------+-----------------------------------------+---------------+ //| Operator         | Name or Meaning                         | Associativity | //+------------------+-----------------------------------------+---------------+ //| ::               | Scope resolution                        | None          | //| ::               | Global                                  | None          | //| [ ]              | Array subscript                         | Left to right | //| ( )              | Function call                           | Left to right | //| ( )              | Conversion                              | None          | //| .                | Member selection (object)               | Left to right | //| ->               | Member selection (pointer)              | Left to right | //| ++               | Postfix increment                       | None          | //| --               | Postfix decrement                       | None          | //| new              | Allocate object                         | None          | //| delete           | Deallocate object                       | None          | //| delete[ ]        | Deallocate object                       | None          | //| ++               | Prefix increment                        | None          | //| --               | Prefix decrement                        | None          | //| *                | Dereference                             | None          | //| &                | Address-of                              | None          | //| +                | Unary plus                              | None          | //| -                | Arithmetic negation (unary)             | None          | //| !                | Logical NOT                             | None          | //| ~                | Bitwise complement                      | None          | //| sizeof           | Size of object                          | None          | //| sizeof ( )       | Size of type                            | None          | //| typeid( )        | type name                               | None          | //| (type)           | Type cast (conversion)                  | Right to left | //| const_cast       | Type cast (conversion)                  | None          | //| dynamic_cast     | Type cast (conversion)                  | None          | //| reinterpret_cast | Type cast (conversion)                  | None          | //| static_cast      | Type cast (conversion)                  | None          | //| .*               | Apply pointer to class member (objects) | Left to right | //| ->*              | Dereference pointer to class member     | Left to right | //| *                | Multiplication                          | Left to right | //| /                | Division                                | Left to right | //| %                | Remainder (modulus)                     | Left to right | //| +                | Addition                                | Left to right | //| -                | Subtraction                             | Left to right | //| <<               | Left shift                              | Left to right | //| >>               | Right shift                             | Left to right | //| <                | Less than                               | Left to right | //| >                | Greater than                            | Left to right | //| <=               | Less than or equal to                   | Left to right | //| >=               | Greater than or equal to                | Left to right | //| ==               | Equality                                | Left to right | //| !=               | Inequality                              | Left to right | //| &                | Bitwise AND                             | Left to right | //| ^                | Bitwise exclusive OR                    | Left to right | //| |                | Bitwise OR                              | Left to right | //| &&               | Logical AND                             | Left to right | //| ||               | Logical OR                              | Left to right | //| e1?e2:e3         | Conditional                             | Right to left | //| =                | Assignment                              | Right to left | //| *=               | Multiplication assignment               | Right to left | //| /=               | Division assignment                     | Right to left | //| %=               | Modulus assignment                      | Right to left | //| +=               | Addition assignment                     | Right to left | //| -=               | Subtraction assignment                  | Right to left | //| <<=              | Left-shift assignment                   | Right to left | //| >>=              | Right-shift assignment                  | Right to left | //| &=               | Bitwise AND assignment                  | Right to left | //| |=               | Bitwise inclusive OR assignment         | Right to left | //| ^=               | Bitwise exclusive OR assignment         | Right to left | //| ,                | Comma                                   | Left to right | //+------------------+-----------------------------------------+---------------+  不要纠结各种常量了，这个世界上唯一不变的就是变化。用API WriteProcessMemory还能修改正运行的其它进程的内存里面的所谓常量呢！

user: user-0
content: 依旧会warning。 pointer const pointer中的const是对第二个pointer起作用， 属于top level const，赋值时可以忽略const，故有与没有不影响。

user: user-2
content: 问题一 已知，const pointer是可以指向non-const pointer的。 同理，我会认为const pointer pointer也可以指向non-const pointer pointer。 //这里是错的 应该是  const pointer const pointer 也可以指向 non-const pointer pointer，或 pointer const pointer 也可以指向 non-const pointer pointer 即  // list-2 {     int a = 10;     int *pa = &a;     const int* const *ppa = &pa;   // here，const是针对于最后一层指针     printf("%d\n", **ppa); }  问题二 你的理解正确 // list-3 {     char *p;     int i = 10;     p = (char*)&i;     *(int*)p = 12; //这里解引用可左值也可右值，所以没问题     printf("%d\n", *p); }

user: user-3
content: 说一下 list-3，(int *)p是强制类型转换，这个没问题，*(int **)&p 就不是了，&p 是取p的地址，程序看是个空指针，不考虑，(int **)&p 强制类型转换，而前面 * 是解引用，得到的是左值，不是右值，这样就合理了。