一下copy自:http://bbs.csdn.net/topics/90234659ios
------------------------------------------------------------------------------------------------------------------- 數組
「兩則C語言技巧」http://tb.blog.csdn.net/TrackBack.aspx?PostId=1120124
第一個技巧在個人環境下不能經過,是個人緣由嗎。
引用:
1. 數組初始化。
常見的數組初始化方法:
int array[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
一般狀況下,這種作法沒有問題。再看看下面這個例子:
enum
{
FRUIT_APPLE,
FRUIT_PEAR,
FRUIT_BANANA,
FRUIT_NR
};
int price[FRUIT_NR] = {20, 25, 30};
這段代碼有個潛在前提,那就是枚舉的順序不能變化。一旦變化,整個邏輯都亂了,這樣的BUG可否查出來要靠運氣。這樣的假設是靠不住的,特別是當枚舉是第三方庫提供的時候,他們調整枚舉的順序後絕對不會通知你。爲了不這樣的潛在隱患,能夠用下面的方法:
Enum
{
FRUIT_APPLE,
FRUIT_PEAR,
FRUIT_BANANA,
FRUIT_NR
};
int price[FRUIT_NR] = { [FRUIT_APPLE] = 20, [FRUIT_PEAR] = 25, [FRUIT_BANANA] = 30};
而個人測試代碼,不行啊:
//用枚舉量作下標初始化數組。
#include <iostream>
enum
{
FRUIT_APPLE,
FRUIT_PEAR,
FRUIT_BANANA,
FRUIT_NR
};
int main()
{
using namespace std;
int price1[FRUIT_NR] = {20, 25, 30};
int price2[FRUIT_NR] =
{
[FRUIT_APPLE] = 20,
[FRUIT_PEAR] = 25,
[FRUIT_BANANA] = 30
};
int i = 0;
cout << "price1:\n";
cout << "apple, " << price1[i++] << ". ";
cout << "pear, " << price1[i++] << ". ";
cout << "banana, " << price1[i] << ". \n";
i = 0;
cout << "price2:\n"
cout << "apple, " << price2[i++] << ". ";
cout << "pear, " << price2[i++] << ". ";
cout << "banana, " << price2[i] << ". \n";
system("PAUSE");
return 0;
}
第二個技巧還不錯。app