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C++ 动态新闻推送第32期

Ts> Overload(Ts...) -> Overload; std::vectorstd::variantlong, float, int, double, long..."; }, [](unsigned int) { return "unsigned int"; }, [](long int) { return "long int"; }, [](long...long int) { return "long long int"; }, [](auto) { return "unknown type"; }, }; for (auto v : vecVariant...'\n'; } std::cout << '\n'; std::vectorstd::variantstd::vectorint>, double, std::string>> //...y)); hash_add(h, std::bit_cast(z)); return h; } size_t myhash_int(float x, float y

4591 0

C++ 中文周刊 2024-03-03 第150期

介绍fs相关api，比如遍历之类的，我就不列出来了 How to write unit tests in C++ relying on non-code files?...冒号表达式 • 减少虚函数使用，你用variant模拟那也是虚函数，不要自欺欺人哈 • inline，可以用[[gnu::always_inline]] • 善用 __builtin_expect •...long set_bit_a(int bit) { return 1 << bit; } static unsigned long set_bit_b(int bit) { return 1U...<< bit; } int main() { printf("sizeof(unsigned long) here: %zd\n", sizeof(unsigned long)); for...::expectedint, std::string> convertToInt(const std::string& input) { int value{}; auto [ptr,

1021 0

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聊聊cmov

大概十几年前 linus对于cmov不屑一顾 https://yarchive.net/comp/linux/cmov.html，性能表现不行测试代码在这里 #include /* How...*/ #define BIT 1 #ifdef CMOV #define choose(i, a, b) ({ \ unsigned long result; \ asm("...main(int argc, char **argv) { int i; unsigned long sum = 0; for (i = 0; i < ITERATIONS;...i++) { unsigned long a = 5, b = 7; sum += choose(i, a, b); } printf("%lu\n",...size, size_t pos) { size_t parent = pos; size_t child; while ((child = 2 * parent + 2) < size)

1201 0

C++数值类型与string的相互转换

long int strtoul (const char* str, char** endptr, int base); #示例 string love="77"; unsigned long ul...const string& str, size_t* idx = 0, int base = 10);long stol (const wstring& str, size_t* idx = 0, int...str, size_t* idx = 0, int base = 10);unsigned long stoul (const wstring& str, size_t* idx = 0, int base...str, size_t* idx = 0, int base = 10);long long stoll (const wstring& str, size_t* idx = 0, int base =...str, size_t* idx = 0, int base = 10);unsigned long long stoull (const wstring& str, size_t* idx = 0

9.8K2 1

C++ 动态新闻推送第46期

C++ 动态新闻推送第46期文章一个variant bug int main() { using namespace std; variant var{...naiveSum(unsigned int n) { auto p = new int[n]; std::iota(p, p+n, 1); auto tmp = std::accumulate...(p, p+n, 0); delete[] p; return tmp; } constexpr int smartSum(unsigned int n) { return (...; case long_enum_name::coding: std::cout << "coding "; break; } #endif } enum class another_long_name...How hard can it be?

4221 0

算法--递归--走台阶问题（2种递归+递归改循环）

溢出，改用 unsigned long #include using namespace std; unsigned long cal(unsigned long n) { if...2.循环代码 #include using namespace std; int main() //循环 { unsigned long n, step, nextStep...) { size_t n; cout << "请输入你要走的台阶数 n :" ; cin >> n; mapunsigned long, unsigned long>...#include #include using namespace std; unsigned long cal(size_t n, size_t stepWalkAway...; unsigned long dynamicProgram(size_t N) { unsigned long left[N+1], right[N+1]; left [1] = 1;

1.9K2 0

malloc.c

long, being aware of the fact that casting an unsigned int to a wider long does not sign-extend...56 + (((unsigned long)(sz)) >> 6): \ ((((unsigned long)(sz)) >> 9) unsigned long)(sz)) >> 6): \ ((((unsigned long)(sz)) >> 9) <= 20)?...size; unsigned long total = 0; int max_fast_bin; /* internal size_t must be no wider...= 0) { size_t a = MALLOC_ALIGNMENT * 2; while ((unsigned long)a unsigned long)alignment

4.8K2 0

C++11中的to_string

(unsigned val); string to_string (unsigned long val); string to_string (unsigned long long val...val); 除此之外，C++11标准库还引入了字符串转整数系列函数： int stoi (const string& str, size_t* idx = 0, int base = 10...); long stol (const string& str, size_t* idx = 0, int base = 10); long long stoll (const...string& str, size_t* idx = 0, int base = 10); unsigned long stoul (const string& str, size_t*...idx = 0, int base = 10); unsigned long long stoull (const string& str, size_t* idx = 0, int base

5412 0

STL之序列式容器（array和vector）

main() { const unsigned int min_wt {100U}; const unsigned int max_wt {250U}; const unsigned...int wt_step {10U}; const size_t wt_count {1 + (max_wt - min_wt) / wt_step}; const unsigned int...min_ht {48U}; const unsigned int max_ht {84U}; const unsigned int ht_step {2U}; const size_t...::arrayunsigned int, wt_count> weight_lbs; std::arrayunsigned int, ht_count> height_ins; //...std::endl; double bmi {}; unsigned int feet {}; unsigned int inches {}; const unsigned

6182 0

Linux 系统调用

long sys_openat2(int dfd, const char __user *filename, struct open_how *how, size_t size); asmlinkage...long sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)...long sys_msync(unsigned long start, size_t len, int flags); asmlinkage long sys_mlock(unsigned long start...__user *, size_t, unsigned); asmlinkage long sys_send(int, void __user *, size_t, unsigned); asmlinkage...(old_sigset_t __user *uset); asmlinkage long sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t

9.9K2 0

CC++ 获取 MAC 地址的几种方法

(DIDD_TYPE_CHAR) * MAX_PATH; static constexpr SIZE_T DIDD_SIZE_FULL = DIDD_SIZE_HEAD DIDD_SIZE_BODY...long count; CloseHandle(hWritePipe); std::string strBuffer(1024 * 10, '\0'); // 准备足够大的缓冲区 if...int)mac[0], (unsigned int)mac[1], (unsigned int)mac[2], (unsigned int)mac[3], (unsigned int)...mac[4], (unsigned int)mac[5]); MACs=buf; } return(MACs); } WMI #define _WIN32_DCOM #include <iostream...vtProp; VARIANT vtProp2; // Get the value of the Name property hres = pclsObj->Get

1.4K2 1

C++学习——int、long、long long, double, long double等的占用空间及取值范围「建议收藏」

unsigned int 0～4294967295 int 2147483648～2147483647 unsigned long 0～4294967295 long 2147483648～2147483647...__int64的最大值：9223372036854775807 __int64的最小值：-9223372036854775808 unsigned __int64的最大值：18446744073709551615...#include #include #include using namespace std; int main() {...: \t" size_t); cout size_t>::max)();...、unsigned、long、unsigned long 、double的数量级最大都只能表示为10亿，即它们表示十进制的位数不超过10个，即可以保存所有9位整数。

3.1K2 0

C++ 动态新闻推送第49期

喜欢扣细节的可以看看另外推荐观看CppCon 2019: Marshall Clow “std::midpoint? How Hard Could it Be?”...]; std::size_t inst_jmp[InstructionCapacity]; }; template std::size_t InstructionCapacity> void...>& program, unsigned char* data_ptr, std::size_t inst_ptr = 0) { if (inst_ptr...::size_t InstPtr = 0> constexpr void execute(unsigned char* data_ptr) { if constexpr (InstPtr >=...std::default_initializable); 类似的编译期单测直接干掉这种小错误 C++ Templates: How to Iterate through

9351 0

C++ 动态新闻推送第58期

; } 学会这种封装思想.虽然不太会用到 Memory-Size Literals constexpr unsigned long long operator""_KiB(unsigned long long...int x) { return 1024ULL * x; } constexpr unsigned long long operator""_MiB(unsigned long long int...x) { return 1024_KiB * x; } constexpr unsigned long long operator""_GiB(unsigned long long int...x) { return 1024_MiB * x; } constexpr unsigned long long operator""_TiB(unsigned long long int x...) { return 1024_GiB * x; } constexpr unsigned long long operator""_PiB(unsigned long long int x)

1973 0

Udacity并行计算课程 CS344 编程作业答案

unsigned int* const d_outputPos, const size_t numElems) { //TODO //PUT YOUR SORT...int* d_inputVals, unsigned int* d_splitVals, const size_t numElems, unsigned...const d_outputVals, unsigned int* const d_outputPos, const size_t numElems...device array for blelloch scan: const int nBlellochBins = 1 unsigned(log((long double)numElems).../log((long double)2) + 0.5); unsigned int* d_blelloch; checkCudaErrors(cudaMalloc((void**)&d_blelloch

1.2K2 0

【C++】size_t全面解析与深入拓展

很多人刚接触时会有疑惑：size_t和普通的无符号整型（unsigned int）有什么关系和区别？为什么在很多地方偏偏要用size_t而不是其他整数类型？...比如，在常见的系统中，size_t可能被定义为： typedef unsigned int size_t; // 在32位系统上 typedef unsigned long size_t;...; // 合法，64位系统可以支持 // unsigned int 示例 unsigned int index = 5000000000; // 溢出，无法表示大于2^32的值...与unsigned int的对比虽然size_t和unsigned int都属于无符号整数类型，但它们有本质区别：特性 size_t unsigned int 定义目的表示大小、索引，与平台无关...示例： int a = -5; size_t b = 10; std::cout std::endl; // 注意：结果可能不符合预期四、小结通过本文的分析可以看出，size_t

1181 0

c++ 日志类线程安全+缓存

::mutex; using std::shared_ptr; #define LOGFILE "log" namespace cyc{ const size_t filename_len...& operatorlong); LogStream& operatorunsigned long); LogStream& operatorlong...long); LogStream& operatorunsigned long long); LogStream& operatorunsigned long v) { formatInteger(v); return *this; } LogStream...::operatorunsigned long long v) { formatInteger(v); return *this; } LogStream& LogStream:

1.3K2 1

arean.c

*h; long diff; #endif { size_t page_mask = malloc_getpagesize - 1; long new_size...(unsigned long) new_size > (unsigned long) HEAP_MAX_SIZE) return -1; if((unsigned long)...#if __STD_C shrink_heap(heap_info *h, long diff) #else shrink_heap(h, diff)...internal_function #if __STD_C heap_trim(heap_info *heap, size_t pad) #else...(size_t size) { mstate a; heap_info *h; char *ptr; unsigned long misalign

7303 0

C++ 动态新闻推送第38期

SSO buffer", 3 }}; std::mapstd::string, int, std::less> trIntMap { { "Hello Super Long String"...unsigned long& start_index, std::uint64_t max) noexcept...-> std::variantstd::uint64_t, std::errc> { constexpr auto is_digit = [](char c) { return '0' long length, unsigned long& start_index) -> std::uint32_t { constexpr...::size_t length) { unsigned long index = 0; auto addr = extract_ipv4_address(str, length, index

6351 0

C++基础数据类型占字节大小分析

测试程序几点说明： signed, unsigned, long和short都隐含了int, 等价于signed int, unsigned int, long int, short int 但注意char...std; int main() { /* signed, unsigned, long和short都隐含了int, 等价于signed int, unsigned int, long...int>::min)() << endl; cout unsigned: \t" unsigned); cout long>::min)() << endl; cout unsigned long: \t" unsigned...: \t" size_t); cout size_t>::max)(); cout

5212 0

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