int>);static_assert(std::is_same_v<decltype((&(foo))('0')),char>);
若违背前条件,则反映于 std::contract_violation 参数的源码位置是由实现定义的。 若违背后条件,则反映于 std::contract_violation 参数的源码位置是函数定义的源码位置。 若违背断言,则反映于 std::contract_violation 参数的源码位置是断言所应用到的语句的源码位置。
如果宽度 或精度 中使用嵌套的替换域,而对应的实参不是整数类型(C++23 前)标准有符号或无符号整数类型(C++23 起),为负,或对于宽度 为零,那么就会抛出std::format_error类型的异常。 floatpi=3.14f;assert(std::format("{:10f}", pi)==" 3.140000");// 宽度 = 10assert(std::format...
assert(std::is_same_v<int,int>);// error: assert does not take two argumentsassert((std::is_same_v<int,int>));// OK: one argumentstatic_assert(std::is_same_v<int,int>);// OK: not a macrostd::complex<double>c;assert(c==std::complex<double>{0,0});// errorassert((c==...
assert(is_inserted);// std::tie and structured bindings:autoposition=[](intw){returnstd::tuple(1*w,2*w);};auto[x, y]=position(1);assert(x==1&&y==2);std::tie(x, y)=position(2);// reuse x, y with tieassert(x==2&&y==4);// Implicit conversions are permitted:std::tuple...
#include <variant>#include <string>#include <cassert>usingnamespacestd::literals;intmain(){std::variant<int,float>v, w;v=12;// v contains intinti=std::get<int>(v);w=std::get<int>(v);w=std::get<0>(v);// same effect as the previous linew=v;// same effect as the previous...
<cassert> Conditionally compiled macro that compares its argument to zero <system_error> (since C++11) defines std::error_code, a platform-dependent error code <cerrno> Macro containing the last error number Strings library <cctype> functions to determine the type contained in character data...
autodb = cppstddb::mysql::create_database();autor = db.statement("select name,score from score").query().rows();autokey ="b";autoi = find_if(r.begin(), r.end(), [key](autorow) {returnrow[0].str() == key; });assert(i != r.end());autorow = *i; cout << row["...
g++编译选项:-std=c++11。包含头文件: #include <thread>:C++多线程库 #include <mutex>:C++互斥量库 #include <future>:C++异步库线程的创建 以普通函数作为线程入口函数:void entry_1() { } void entry_2(int val) { } std::thread my_thread_1(entry_1); std::thread my_thread_2(entry_2, 5...
std::contracts::assertion_kindC++ 工具库 契约支持 在标头 <contracts> 定义 enum class assertion_kind : /* 未指定 */ { pre = 1, post = 2, assert = 3 }; (C++26 起) std::contracts::assertion_kind 的枚举项与契约断言的语法形式一一对应,含义如下: ...