判断是否有某键，不用count而是用find，因为如果存在某键的话，count会返回键的所有个数，也就是会遍历所有，而不是找到了就返回 []向Fr中插入键n，值调用默认构造函数 if (Fr.find(n) == Fr.end()) { Fr[n]; }

调用可以和定义或申明不在一起 不分离申明和定义都放在.h文件中函数模板 template <typename T> void testprint(T i) { std::cout << i << std::endl; } 类模板 template <typename T> class A { T ...

指令速查中文部分（从这里猜测用什么关键词去下面的官方文档中搜）https://packagewjx.github.io/2018/11/12/sse-note/官方（这个超级好，搜索迅速，给了描述、实现指令、头文件、对应指令集标准等）https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html

栈：alignas specifier (since C++11) alignas specifier (since C++11) - cppreference.com Specifies the alignment requirement of a type or an object. Syntaxalignas( expression ) \1) expression must ...

new expression - cppreference.com Creates and initializes objects with dynamic storage duration, that is, objects whose lifetime is not necessarily limited by the scope in which they were created....

Memory-mapped fileA memory-mapped file is a segment of virtual memory[1] that has been assigned a direct byte-for-byte correlation with some portion of a file or file-like resource. This resource ...

__m128i__m128i | Microsoft Learn The __m128i data type, for use with the Streaming SIMD Extensions 2 (SSE2) instructions intrinsics, is defined in <emmintrin.h>. eg: /usr/local/gcc-9.3.0/lib...

main.c测试内容 #include <stdio.h> int main() { printf("hello\n"); return 0; } ubuntu装环境sudo apt update sudo apt install build-essential sudo apt install gcc-multilib ...

装c++环境gcc和g++都要以ubuntu为例 sudo apt-get instal gcc sudo apt-get instal g++ #没装会报错找不到比如iostream头文件 配置vscode https://blog.csdn.net/jinking01/article/details/106186575 装c/c++、c++ IntelliSense插件version...

man page: https://man7.org/linux/man-pages/man2/open.2.html const char* file = "test_file.txt"; int pfd = open(file, O_WRONLY | O_CREAT | O_APPEND, 0777); O_WRONLY：只写O_CREAT：如果不存在则创建O_...