快速输入输出功能 [英] Fast input output function
问题描述
#define getcx getchar_unlocked
inline void inp( int &n )//fast input function
{
n=0;
int ch=getcx();int sign=1;
while( ch < '0' || ch > '9' ){if(ch=='-')sign=-1; ch=getcx();}
while( ch >= '0' && ch <= '9' )
n = (n<<3)+(n<<1) + ch-'0', ch=getcx();
n=n*sign;
}
Hi我一直使用上述函数来输入各种编码比赛,但是永远不能理解为什么它是快。我知道逻辑,但不知道它的坚牢的概念。例如,这行是什么#define getcx getchar_unlocked。此外,我不知道任何快速输出函数,所以有任何快速输出函数也
Hi I have been using the above function for input in various coding contests but was never able to understand why is it fast. I know the logic but don't know the concept of it's fastness. For example what is this line doing "#define getcx getchar_unlocked" . Also I don't know any fast output function so is there any fast output function also
推荐答案
#define
使用预处理器使 getcx
成为函数 getchar_unlocked()
,这是一个非锁定字符阅读功能。
The #define
uses the preprocessor to make getcx
be a short-hand for the function getchar_unlocked()
, which is a non-locking character-reading function.
这是一个有点可怕,你参加了几个编码比赛,没有理解这个漂亮的基本的C。
It's a bit awesome that you've competed in several coding contests without understanding this pretty basic piece of C.
手册页我链接到上面提到的 putc_unlocked()
听起来几乎是一样的东西,但输出。
The manual page I linked to above mentions putc_unlocked()
which sounds like pretty much the same thing but for output.
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