I was writing a sample code on NetBeans and I realized that using std::foo does not work on NetBeans. It gives a "unresolved identifier error". This is the sample code below;
#include <cstdlib>
#include <iostream>
#include <vector> //Required whenever you use vectors
/*
*
*/
using std::vector;
using std::cout;
using std::endl;
int main(int argc, char** argv) {
vector<int> integers (4, 100); // Creates a vector [100 100 100 100]
cout << integers[0] << endl;
return 0;
}
The code builds and runs but the error is still visible on the text page.
Related
My code is a basic HelloWorld but fails to compile when I use cout<<endl.
I'm using Microsoft visual studio fresh download and created a console application for my first test project.
// Test1ConsoleApplication.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <string>
#include <iostream>
//#include <ostream>
using namespace std;
int main()
{
string s = "hello world!!";
cout << "lets see: " << s << endl;
return 0;
}
It generates a
"C1001" at line 1.
Replacing "endl" with ""\n"" works though.
You don't need the precompiled header #include <stdafx.h> so you can safely get rid of it. Also get rid of using namespace std; because it pollutes the global namespace. Try something like this. There's no reason it shouldn't work.
#include <string>
#include <iostream>
using std::string;
using std::cout;
using std::endl;
int main()
{
string s = "hello world!!";
cout << "lets see: " << s << endl;
return 0;
}
In Visual Studio you can disable use of the precompiled header in the project settings.
I do not see what the problem is. Both options compile and execute for me.
RexTester cppOnline
// Test1ConsoleApplication.cpp : Defines the entry point for the console application.
//
//#include "stdafx.h"
#include <string>
#include <iostream>
//#include <ostream>
using namespace std;
int main()
{
string s = "hello world!!";
cout << "lets see: " << s << endl;
cout << "lets see: " << s << "\n";
return 0;
}
So idk what was causing the error but it was fixed after pasting imports to the "stdafx.h" header file and then delete them...
I'm having issue in the ifstream function, I have tried using the argv[1] as parameter but wont load the map, the map is located in the same folder of main code.
I'm stucked here and can not debug.
#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <fstream>
#include <sstream>
using namespace std;
int main (int argc, char *argv[]){
int h;
int w;
int var;
string inputLine;
ifstream f;
f.open("map.pgm",ios::in);
if (!f){
cout << "error" << endl;
exit(1);
}
I'm using Visual Studio 2017
Change this line:
if (!f){
by this:
if (!f.is_open()){
BTW you can check current directory path with GetModuleFileName
Super confused as to what is throwing the error when I try to compile my code. I'm currently trying to test a function I wrote by printing out the values it should extract from a file.
gameboard.cpp
#include "stdafx.h"
#include <iostream>
#include <sstream>
#include <fstream>
#include "error.h"
using namespace std;
int boardDim(ifstream & inputFile, unsigned int x, unsigned int y) {
inputFile.open; //error is thrown here
if (!(inputFile.is_open())) {
throw fileNotOpen;
}
else {
stringstream output(inputFile.getline); //error is also thrown here
if (output >> x) {
if (output >> y) {
return success;
}
return secBoardVarErr;
}
return firstBoardVarErr;
}
cout << x << endl;
cout << y << endl;
}
gameboard.h
#ifndef GAMEBOARD_H
#define GAMEBOARD_H
#include <iostream>
using namespace std;
//takes in dimensions of board from file
int boardDim(ifstream &, unsigned int, unsigned int);
#endif !GAMEBOARD_H
main function
#include "stdafx.h"
#include "functions.h"
#include "gamepieces.h"
#include "gameboard.h"
#include "error.h"
int main(int argc, char * argv[])
{
ifstream x("test.txt");
int test = 0;
cout << boardDim(x, 0, 0) << endl;
return success;
}
I'm only testing the function I declared and defined in the gameboard header and source files, so the other included files will be used in the future but have already been tested and are not throwing errors when I compile and run it.
Thank you!
inputFile.open is a function, same with inputFile.getline, so what you have here is a syntactic error. The correct syntax is:
inputFile.open()
and
inputFile.getline()
I'm trying to get the monitor in order to check if is off or not.
Before checking with GetDevicePowerState, I'm trying to retrieve monitor in this way:
#include <cstdlib>
#include <iostream>
#include <windows.h>
#include <winuser.h>
using namespace std;
int main(int argc, char *argv[])
{
POINT* p = new POINT;
p->x=0;
p->y=0;
HMONITOR* monitor = MonitorFromPoint(p,DWORD.MONITOR_DEFAULTTOPRIMARY);
system("PAUSE");
return EXIT_SUCCESS;
}
But it continually gives me:
main.cpp `MonitorFromPoint' undeclared (first use this function)
Where have I gone wrong?
Your code has a number of problems, but none of them should cause the error message you're seeing. Here's code with some corrections, and a little more added to show at least some kind of result from the test:
#include <iostream>
#include <windows.h>
int main(int argc, char *argv[])
{
POINT p{ 0, 0 };
HMONITOR monitor = MonitorFromPoint(p, MONITOR_DEFAULTTONULL);
if (monitor == NULL)
std::cout << "No monitor found for point (0, 0)\n";
else {
MONITORINFOEX info;
info.cbSize = sizeof(info);
GetMonitorInfo(monitor, &info);
std::cout << "Monitor: " << info.szDevice << "\n";
}
}
I've tested this with both VC++ 2013 and MinGW 4.8.1, and in both cases it's compiled and run without any problems, producing:
Monitor: \\.\DISPLAY1
...as its output in both cases.
I am working on an assignment and I need to create pipes so that other programs handle different functions. I am able to pipe through the command line no problem, thats easy. However using dup2 and execl have been tricky for me. At one point I was able to get output from one part of my program but it wasn't reading anything in from another part.
here is what i have:
pipeline.cpp
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <cstdlib>
#include <iostream>
#include <cctype>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include<iostream>
#include<cstdlib>
#include<unistd.h>
#include<iomanip>
#include <sys/wait.h>
using namespace std;
int main(int argc, char *argv[])
{
int number = atoi(argv[1]);
int x2ypipe[2];
pipe(x2ypipe);
if(x2ypipe==0){
cout<<"ERROR:"<<errno<<endl;
}
pid_t xchild =fork();
if(xchild==0){
dup2(x2ypipe[1],STDOUT_FILENO);
close(x2ypipe[0]);
close(x2ypipe[1]);
execl("./part1.cpp","part1.cpp", (char *)NULL);
}
pid_t ychild =fork();
if(ychild==0){
dup2(x2ypipe[0],STDIN_FILENO);
close(x2ypipe[0]);
close(x2ypipe[1]);
execl("./part2.cpp", "part2.cpp", (char *)NULL);
}
close(x2ypipe[0]);
close(x2ypipe[1]);
wait(NULL);
wait(NULL);
part1.cpp
#include<iostream>
#include<cstdlib>
#include<unistd.h>
#include<iomanip>
using namespace std;
int main(int argc, char *argv[])
{
int number = atoi(argv[1]);
for (int k = 1; k <= 9; k++)
{
cout << k << " " << flush;
sleep(1);
}
return 0;
}
part2.cpp
#include <iostream>
#include <cstdlib>
#include <unistd.h>
#include <iomanip>
using namespace std;
int main()
{
int number;
while (cin >> number)
{
cout << 2 * number - 1 << " " << flush;
}
return 0;
}
Ok so pipeline.cpp : forks twice and creates a pipe between the two children. Then each use excel to replace its process with the programs part1 and part2. So my understanding is that part1 program would run and anything it outputs will be picked up by the second child which runs part2 and from there part two would output normally since it's output descriptor wasn't changed. Am I missing or misusing something here?
I noticed a couple of things:
You're not passing the number to the part1 process when you exec it
You're not checking for failure from execl() or any of the other OS functions
I think once you do these two things, you'll find out what the real problem is. I won't just tell you what the answer is, because it's worthwhile learning how to diagnose such problems yourself. (I was able to run your code successfully with only minor modifications. The problem does not lie in how you're handling the pipes and file descriptors.)
I think you need to return 0; after your exec calls. But I am even more lost than you it seems.