int func(int aa[4]) { return sizeof(aa);}

int func(int aa[4]) { return sizeof(aa);}

返回值为几何??

偶遇此问题，顺便在标准中找到了相关描述。

C99

A declaration of a parameter as ‘‘array of type’’ shall be adjusted to ‘‘qualified pointer to type’’, where the typequalifiers (if any) are those specified within the [ and ] of the array typederivation. If the keyword static also appears within the [ and ] of the arraytype derivation, then for each call to the function, the value of the corresponding actual argument shall provide access to the first element of anarray with at least as many elements as specified by the size expression.

C++2003

After determining the type of each parameter, any parameter of type “array of T” or “function returning T” is adjusted to be “pointer to T” or “pointer to function returning T,” respectively.

Parameter declarations that differ only ina pointer * versus an array [] are equivalent. That is, the array declarationis adjusted to become a pointer declaration (8.3.5). Only the second andsubsequent array dimensions are significant in parameter types (8.3.4).[Example:

int f(char*);

int f(char[]); // same as f(char*);

int f(char[7]); // same as f(char*);

int f(char[9]); // same as f(char*);

int g(char(*)[10]);

int g(char[5][10]); // same as g(char(*)[10]);

int g(char[7][10]); // same as g(char(*)[10]);

int g(char(*)[20]); // different from g(char(*)[10]);

—end example]