When debugging an app using std::cout to print something, nothing appears in the debug console (3rd tab, not external console). One of the exceptions seems to be the use of std::endl:
#include <iostream>
#include <Windows.h>
using namespace std;
int main() {
while(true) {
Sleep(500);
std::cout << "Hello world!" << std::endl; // Works
}
}
#include <iostream>
#include <Windows.h>
using namespace std;
int main() {
while(true) {
Sleep(500);
std::cout << "Hello world!\n"; // Doesn't work
// std::cout << "Hello world!"; // Doesn't work
// std::cout << "Hello world!" << std::flush; // Doesn't work
}
}
In the first example our lines appear over time, while on the second doesn't appear at all (or the console refreshes somewhere around 60 secs). I think this is a bug but I'm not sure, so what is a workaround? Maybe I have to configure something instead? I found this problem while working on something else: C++: cannot see output in VS Code while debugging
Edit
The problem is what to do when u wanna output something without a new line
I recently started using Eclipse CDT (version 2019-03) with the Cygwin toolchain and have noticed some bizarre behaviour when using the debugger.
Under the debugger the following program behaves as you would expect
#include <iostream>
int main()
{
std::cout << "hello world\n" << std::flush;
}
However the following produces no output
#include <iostream>
int main()
{
std::cout << "* world\n" << std::flush;
}
And for the following the output is world
#include <iostream>
int main()
{
std::cout << "# world\n" << std::flush;
}
This behaviour is completely consistent and reproduceable. Does anyone have any explanation or workarounds?
I downloaded Clion and all packages which I needed to work (I hope) and IDE doesn't compile "Hello World" program :(
Code:
#include <iostream>
int main() {
std::cout << "Hello, World!" << std::endl;
return 0;
}
Build errors:
https://pastebin.com/J5UA9HpX
Any ideas? Regards, Dziura.
Sorry for bad English
I am starting with C++ (Visual Studio 2015 and Windows 8.1), with this simple code:
#include <iostream>
using namespace std;
int main()
{
cout << "Hello world" << endl;
return 0;
}
But, the output screen shows nothing!, what shall I do?
Thanks in advance.
In Visual Studio, start the program with Ctrl-F5 and it will run and pause automagically for you. No additional code needed.
Your code is perfectly fine but the program currently only prints and exits right after, because this can happen very fast you might not be able to even see it,try pausing it :
#include <iostream>
using namespace std;
int main()
{
cout << "Hello world" << endl;
cin.get();
return 0;
}
Also, make sure your Anti Virus isn't blocking Visual Studio.
Your code is just fine, however, if you execute it as a cmd program, the program window will close immediately, you might not be able to even see the output. You can write extra code to solve this problem by "pausing" the program:
#include <iostream>
#include <windows.h>
using namespace std;
int main()
{
cout << "Hello world" << endl;
system("PAUSE");
return 0;
}
if you don't like include a windows.h file every time you type, you can add a "cin.get();" in the end of the code. But to be honest, since you are just a beginner, the coolest way I think you should try, is not to use Visual Studio to learn C/C++ but to install CodeBlocks(a simple but effective IDE) to write some codes that are not so long. You know, VS is for huge and complex projects and some practical program developing.
Another solution, platform dependent. My answer is for those of you who just need test pause for debugging purposes. It's not recommended release solution!
windows
#include <iostream>
int main()
{
std::cout << "Hello world" << endl;
system("pause");
return 0;
}
linux (and many alternatives)
#include <iostream>
int main()
{
std::cout << "Hello world" << endl;
system("read -rsp $'Press enter to continue...\n'");
return 0;
}
Detecting paltform
I used to do this on programming homework assignments, ensuring this only happens on windows:
#include <iostream>
int main()
{
std::cout << "Hello world" << endl;
#ifdef _WIN32
system("pause");
return 0;
}
Here's a good cheatsheet for ifdef macros and operating systems: http://sourceforge.net/p/predef/wiki/OperatingSystems/
The program exits on return 0; and window closes. Before this, you must pause the program. E.g you can wait for an input.
Here is a snippet from my code to do this. It works in both windows and linux.
#include <iostream>
using std::cout;
using std::cin;
// Clear and pause methods
#ifdef _WIN32
// For windows
void waitForAnyKey() {
system("pause");
}
#elif __linux__
// For linux
void waitForAnyKey() {
cout << "Press any key to continue...";
system("read -s -N 1"); // Continues when pressed a key like windows
}
#endif
int main() {
cout << "Hello World!\n";
waitForAnyKey();
return 0;
}
I am new to C++. I downloaded and run Dev-C++ and I write and run F9 this:
#include <iostream>
using namespace std;
int main()
{
cout << "Hello, world!";
return 0;
}
But no "Hello, world!" is printed, why?
Many IDE users have this problem. The program runs but it closes before you can see its results on the screen. One portable fix is to add this at the bottom of main before you return:
std::cin.get();
That way it will wait for you to enter some text before it exits.
#include <iostream>
using namespace std;
int main()
{
cout << "Hello, world!";
getchar();
return 0;
}
Add getchar() at the end of your program as a simple "pause-method" as consoles seems to close so fast, so you need to "delay" to see your console.
The output is printed to a terminal, and you don't have a newline etc.... very unlikely that you will see it, so
Add a newline to the output
make sure you have time to read the output before the terminal window closes (add a sleep or something)
Don't use using namespace as that is a bad practice and will lead to trouble in your programming.
So like;
#include <iostream>
#include <unistd.h>
int main()
{
std::cout << "Hello, world!" << std::endl;
sleep(2);
return 0;
}