在知道哪个发生概率更高的情况下,有if时使用likely和unlikely让代码运行更快。 likely和unlikely是两个宏,当有if-else分支时告诉编译器,哪个条件更加有可能发生。likely代表if分支大概率会发生,unlikely代表if分支大概率不会发生。 #definelikely(x) __builtin_expect(!!(x), 1) #defineunlikely(x) __builtin_...
1.likely和unlikely 这是两个宏,当有if-else分支时,告诉编译器,哪个条件更加有可能发生。对if-else分支结构进行优化。likely代表if分支大概率会发生,unlikely代表if分支大概率不会发生。 #define likely(x) __builtin_expect(!!(x), 1) #define unlikely(x) __builtin_expect(!!(x), 0) 1. 2. __bui...
if( !!fun1() != !!fun2() ) printf("success");“!!” 可以将条件转换为 bool 值,下面这两种写法是等价的: b = cond?1:0;// 等价于b = !!cond;likely 与 unlikely 宏的实例 现在我们一起看一下 likely 与 unlikely 宏的作用,写出C语言代码如下,请看: #define likely(x) (__builtin_expec...
unlikely.cpp: 1#include<stdio.h>2#include<stdlib.h>34#definelikely(x) __builtin_expect(!!(x), 1)//gcc内置函数, 帮助编译器分支优化5#defineunlikely(x) __builtin_expect(!!(x), 0)67intmain(intargc,char*argv[]){8intx =0;9x = atoi(argv[1]);1011if(unlikely(x ==3)){//告诉...
If I work in a small factory it is not _ for me to gain much experience. A kindly B usually C likely D lively 答案 句意是如果我在一家小工厂工作,我不太可能获得很多经验。kindly意为友善地,usually意为经常,likely意为可能地,lively意为生动的,活泼地,结合句意是我不太...
C If you meet a British person in the street, it is very likely that he or she will apologize whether it is his or her fault or not.It seems that Britain is becoming a nation where everyone is saying sorry. Almost each person says sorry about eight times each day-and one in eight ...
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if(((x-minx)|(maxx-x))>=0)...如果语言警察们担心有符号整数回环是未定义行为的话，可以写成...
This likely represents a source of variability in [11C]ABP688 studies and could have relevance for sex differences in cognitive-behavioral functions and neuropsychiatric disorders. 展开 关键词:Gender Metabotropic glutamate receptors PET mGluR5 DOI: 10.1007/...