Here is my c++ code to read an integer, double it and then print it out on the screen:
#include
<iostream>
int doubleNumber(int x) { return 2 * x; } int main() { using namespace std; int x; cin >> x; cout
<< doubleNumber(x) << endl; return 0; }
I am compiling it using:
g++ -o example9 example9.cpp
It seems it is fine and it creates the object file but it is impossible to run the file using the following command:
./example9
In fact it does nothing (not even an error message)
What I am doing incorrectly?
Your help is appreciated.
When you say it is "impossible to run the file", I expect you are seeing something like the following:
$ ./example9
_
where I have indicated the cursor position with _ (just sitting there, on the next line, not doing anything except blinking). In this case, your program is running fine. It is waiting for you to type a number (the cin >> x statement). Type a number and press Enter.
Related
Here is a program. Its only purpose is to delete the line printed, after some user input.
main.cpp
#include <iostream>
#define ESC_PREV_LINE "\e[F"
#define ESC_CLEAR_TO_END "\e[K"
int main(){
int i;
std::cerr << "Some input to clear: " << std::flush;
std:: cin >> i;
std::cerr << ESC_PREV_LINE ESC_CLEAR_TO_END << std::flush;
}
Inside Xcode, if the user were to input 2, this is the output:
Some input to clear: 2
[F[KProgram ended with exit code: 0
If compiled in terminal, using: g++ -std=c++20 main.cpp -o test, the output is cleared after user input, right before the program exists, and the shell looks like the program never ran.
How can I include this functionality within Xcode? I am writing a program that requires it, but developing inside Xcode, and it would be highly inconvenient to have to swap to the terminal just to test my program output.
I have tried updating my g++ installation but there has been no solution.
Here is the code.
#include <iostream>
using namespace std;
#include<string>
#include <cstring>
int main()
{
char str[100];
cout << "Enter a string: ";
cin>>str;
cout << "You entered: " << str << endl;
cout << "\nEnter another string: ";
cin>>str;
cout << "You entered: "<<str<<endl;
return 0;
}
The output that this code shows is:
Check the terminal
Please give me a solution or at least a reason for this. I am new to Stack Overflow so please free to correct me if I made any mistake in the post. [This problem only happens in vs code but works in online gdb compiler.]
Edit:After I tried executing this in the cmd line this what it shows
cmd line execution
The output you're seeing is from some kind of makefile. You didn't say how you're trying to build the file so it's hard to say what caused the issue.
However, you can simply compile your file directly by typing g++ hgg.cpp -o hgg in the command shell
After writing the code, switch to Command Prompt (Cntrl + x) move to the directory, in which the C++ program is present.
Then run the following:
g++ -Wall filename.cpp -o filename
If nothing is printed on the console, then your code is syntactically correct. Then do the following:
filename.exe
It should work now.
During debugging Eclipse doesn't "see" INPUT from built-in console, just ignores it. Simple example:
#include <iostream>
using namespace std;
int main() {
int a;
cin >> a;
cout << a << endl;
cin >> a;
cout << a << endl;
return 0;
}
works perfectly fine when just run, but when I try to debug it, first "data on input"(?) is always a number around 40, and only zeros next, no matter what i will write to console.
So program executes, first variable is set to ~40 and all next to zeros.
Output works fine, values are written to console, only input doesn't work.
I work on Windows 10 and use MinGW.
Thanks in advance.
#EDIT
Everything works, when I use native Windows console
(.gdbinit file with set new-console on line)
Im just starting with C++ and I wanted to try running this test... When I try compiling the code it just gives an error saying (lldb):
#include <iostream>
using namespace std;
//---------My Function--------//`
int addNums(int x, int y){
int answer = x + y;
return answer;
}
int main(int argc, const char * argv[]){
// insert code here...
/*
int num;
cin >> num;
cout << num;
cout << "\n";
char hm[] = "eef";
cout << hm[2] << endl;
*/
cout << addNums(1, 2);
return 0;
}
If by "Build" you mean you clicked the Play button - the leftmost button in the toolbar - then this is going to build and run your code. The build probably went fine. You can check that the build went okay by switching to the Reports navigator (the one with the speech bubble icon) and click on the latest Build report... If you want to build without running, Cmd-B is what you want to do.
Anyway, if you asked to build & run, and the build went okay, Xcode will start your program in the debugger, which will switch to the Debugger UI. Since your program just prints something and exits, the Debugger should have just printed "3" in the Debugger Console and exited. Not sure why you are seeing an lldb prompt, that is not what I see.
You might try setting a breakpoint, and see what the debugger looks like when you hit the breakpoint.
#include <iostream>
using namespace std;
int main()
{
int x = 42;
cout << x; // This line doesn't print! Why?
return 0;
}
Screenshot of Visual C++: http://bildr.no/image/ZlVBV0k0.jpeg
This code gives me nothing but a black console window that flashes by when I click on debug. Isn't the number 42 supposed to be printed in the console window? This is my first application in C++. I have experience in C# from high school.
EDIT:
Now I have tried this code:
// Primtallsgenerator.cpp : Defines the entry point for the console application.
//
#include <iostream>
using namespace std;
int main()
{
int x = 42;
cout << x << endl; // This line doesn't print! Why?
cin >> x;
return 0;
}
It still doesn't work. Screenshot of the code here: http://bildr.no/image/ODNRc3lG.jpeg
The black windows still just flashes by...
Two things to note:
First, you are not forcing the buffer to flush, so there is no guarantee the output is being sent to the screen before the program ends. Change your cout statement to:
cout << x << endl;
Second, Visual Studio will close the console when it ends (in Debugging mode). If you do not debug it (Ctrl-F5 by default), it will keep the console open until you press a key. This will allow you to see the output. Alternatively, you can add a cin.get() before your return statement which will force the program to wait for a character to be in the input stream before the program is allowed to exit.
It did print the message, it was just too fast for you to see.
add this command:
cin >> x;
or this one
while(true) {}
before the return statement.
Yes, it will print the number. Then the program ends, and the console window is closed. Run it in the debugger, and put a breakpoint on the return 0; line. Then you'll see it.
This code should work fine:
#include <iostream>
#include <stdio.h>
using namespace std;
int main()
{
int x = 42;
cout << x;
getchar();
return 0;
}
Also check this documentation about getchar().
I recommend to use system pause at the end before the "return 0" statement like this:
system("PAUSE");
This is cleaner and much more effective.
If you are working with a console application in Visual Studio, you have to go to your project's linker properties and set your SubSystem setting to CONSOLE.
And get a habit of running your code without a debugger (Ctrl+F5 by default) when you don't need the debugger. That way the console window will not flash and disappear by itself.