cout

问题 int a = 1, b = 2; int c = a*b + b==0; // c = 0 cout << a*b + b==0; // outputs 4 c evaluates to 0 because the operator precedence of the * and + operators is higher than == as a result of which c essentially evaluates to (a*b+b)==0 which is false. Why does putting the same expression in a cout statement output 4? 回答1: Because the precedence of these operators are operator* > operator+ > operator<< > operator== . Then cout << a*b + b==0; is equivalent with (cout << ((a*b) + b)) == 0; . Then the

问题 int a = 1, b = 2; int c = a*b + b==0; // c = 0 cout << a*b + b==0; // outputs 4 c evaluates to 0 because the operator precedence of the * and + operators is higher than == as a result of which c essentially evaluates to (a*b+b)==0 which is false. Why does putting the same expression in a cout statement output 4? 回答1: Because the precedence of these operators are operator* > operator+ > operator<< > operator== . Then cout << a*b + b==0; is equivalent with (cout << ((a*b) + b)) == 0; . Then the

来源： https://stackoverflow.com/questions/62097474/why-does-a-percentage-appear-at-the-end-of-the-output-to-standard-out-but-not

问题 From http://www.cplusplus.com/reference/iostream/cout/: By default, most systems have their standard output set to the console, where text messages are shown, although this can generally be redirected. I've never heard of a system where stdout is anything other than a console window, by default or otherwise. I can see how redirecting it might be beneficial in systems where printing is an expensive operation, but that shouldn't be an issue in modern computers, right? 回答1: On most systems you

问题 Is there a way to print the value of a constexpr or #define d value at compile time? I want the equivalent of std::cout << , or some way to do something like constexpr int PI_INT = 4; static_assert(PI_INT == 3, const_str_join("PI_INT must be 3, not ", const_int_to_str(PI_INT))); Edit: I can do some basic compile-time printing with constexpr s, at least on gcc by doing something like template <int v> struct display_non_zero_int_value; template <> struct display_non_zero_int_value<0> { static

问题 I'm trying to write a program in C++ which will be responsible for simulating blinkers in cars. I want it to be simple and to compile it in a console window. Is it possible to create one thread for input which will be always active and second for output that will run simultaneously? I wanted to use threads to solve this but it doesn't work as I would like. I have a little trouble to understand threads. If anyone could help me to fix this I would be grateful. int in() { int i; cout<<"press 1

问题 I am used to Eclipse CDT where the output of a program (using cout) is written to the "Console" window inside Eclipse. Now I switched to Visual Studio 2013. When creating a simple C++ "Console Application" like #include "stdafx.h" #include <iostream> using namespace std; int _tmain(int argc, _TCHAR* argv[]) { cout << "hello world" << endl; cin.get(); return 0; } the application is "run in the Dos console", i.e. when I press "Run" Visual Studio opens a small Dos window and runs the program

问题 I have a program where I use cout to emit debug information. The code is executed in the initialization of a static global variable, i.e. quite early in the program execution. When I use my own build script to build the program, it segfaults at the first use of cout (only a string literal is shifted into cout, so it cannot be the value). I used valgrind to check for earlier writes to invalid locations, but there are none (and there is also no code that would be likely to generate those writes

问题 I have a program where I use cout to emit debug information. The code is executed in the initialization of a static global variable, i.e. quite early in the program execution. When I use my own build script to build the program, it segfaults at the first use of cout (only a string literal is shifted into cout, so it cannot be the value). I used valgrind to check for earlier writes to invalid locations, but there are none (and there is also no code that would be likely to generate those writes

问题 I have a program where I use cout to emit debug information. The code is executed in the initialization of a static global variable, i.e. quite early in the program execution. When I use my own build script to build the program, it segfaults at the first use of cout (only a string literal is shifted into cout, so it cannot be the value). I used valgrind to check for earlier writes to invalid locations, but there are none (and there is also no code that would be likely to generate those writes