Web笔者刷力扣发现的一个函数,题目是剑指offer15题-二进制中1的个数。 该函数是C++自带的库函数,内部实现是用查表实现的。 作用:统计数字在二进制下“1”的个数。题目如下: class Solution { public: int hamming… WebMar 14, 2024 · 在C或C++中,可以直接使用__builtin_popcount函数。. 其语法如下:. __builtin_popcount (unsigned int x) 其中,x为要计算1的个数的无符号整数。. 该函数会返回x的二进制下1的个数。. 例如,以下代码用于计算x二进制下的1的个数:. unsigned int x = 10; // x的二进制为 1010 int count ...
__builtin_popcount - Codeforces
WebJul 30, 2024 · Builtin functions of GCC compiler in C - In the GCC compiler there are some builtin functions. These functions are like below.Function _builtin_popcount(x)This builtin function is used to count the number of 1s in an integer type data. Let us see an example of _builtin_popcount() function.Example Live Demo#include using namespac WebAug 12, 2024 · 交给编译器就可以针对特定的硬件指令集优化,比如这个popcount函数,在x86平台上编译器就能直接用POPCNT这条指令而不是使用C语言位运算做。 其他还有很多builtin函数原理都一样,只不过这个东西一般没有移植性,使用时要注意。 gray hair accessories
C/C++中__builtin_popcount()的使用及原理-阿里云开发者社区
WebMay 2, 2024 · r = __builtin_popcount (x); for (r = 0; x; x &= x-1) r ++; lg = 32-__builtin_clz (x); lg = __lg (x) + 1; 在头文件 里提供了 popcount 和 bit_width 这两个函数,缩短 … WebJun 21, 2024 · Count unset bits of a number. Given a number n, count unset bits after MSB (Most Significant Bit). Input : 17 Output : 3 Binary of 17 is 10001 so unset bit is 3 Input : 7 Output : 0. Recommended: Please try your approach on {IDE} first, before moving on to the solution. A Simple Solution is to traverse through all bits and count unset bits. WebIn this article, we have explored about __builtin_popcount - a built-in function of GCC, which helps us to count the number of 1's (set bits) in an integer in C and C++. POPCNT is the assemby instruction used in __builtin_popcount. The population count (or popcount) of a specific value is the number of set bits in that value. chocolife cnpj