#include <iostream> using namespace std; int main(int argc, char* argv[]) { char *a = "abcde"; char sz1[] = "abc"; char sz2[] = {"abc"}; char sz3[] = { 'a', 'b', 'c' }; printf_s( "%d %d %d %d", _sizeof(a), _countof(sz1), _countof(sz2), _countof(sz3) ); cout<<endl; int b[] = {1,2,3}; cout<<sizeof(b)<<" "<<_countof(b)<<endl; return 0; } 程序输出:4 4 4 3 12 3 //***************************************************************************// _countof 是 C++中计算一个固定大小数组长度的宏,比如: T arr[10]; for( size_t i = 0; i<_countof(arr); --i ) do_something(); // 对于固定大小数组计算起来非常方便。 /* _countof helper */ #if !defined(_countof) #if !defined(__cplusplus) #define _countof(_Array) (sizeof(_Array) / sizeof(_Array[0])) #else extern "C++" { template <typename _CountofType, size_t _SizeOfArray> char (*__countof_helper(UNALIGNED _CountofType (&_Array)[_SizeOfArray]))[_SizeOfArray]; #define _countof(_Array) sizeof(*__countof_helper(_Array)) } #endif #endif
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