I am trying to make a graph using graphics.h in c++. I was following a tutorial on youtube. It seems that either due to the age of the video (perhaps the syntax has changed slightly?) or a problem on my end; I cannot even get a separate window for my graph to open. I am in completely uncharted waters for me as the limit of my coding knowledge is what you would expect to learn from a first-semester coding class. I am using DEV C++ and am compiling using "TDM-GCC 4.9.2 32-bit Release" (because the 64 bit release gives me an error in "Makefile.win" that scares me) and my program exits with a return value of 3221225477. What am i doing wrong?
#include"graphics.h"
#include<math.h>
#include<conio.h>
#include<iostream>
using namespace std;
int main() {
initwindow(800,600);
int x,y;
line(0,300,getmaxx(),300);
line(400,0,400,getmaxy());
float pi=3.14159;
for(int i=-360;i<=360;i++){
x=(int)400+i;
y=(int)300-sin(i*pi/100)*25;
putpixel(x,y,WHITE);
}
getch();
closegraph();
return 0;
}
According to your issue and exit-code, the return value in hex is 0xC0000005 or STATUS_ACCESS_VIOLATION. But most developers didn't even bother to learn out-dated legacy API and I can not help you to find the exact line (use debugger, it shows you the exact line, still not the reason).
But to answer your question in the title, well, according to what free framework one uses (Qt or XWidget), the method differs, for Qt (which I would recommend) simply override paint-event and use QPainter renderer to show your QPath data.
Don't reinvent the wheel (or render-system in this case), your course and/or book may soon introduce you to one of the mentioned frameworks.
Related
I use MinGW64 to compile c++ programs. But since I upgraded to Windows 10, I found my c program output Chinese will be garbled code.
I follow the online method, adding a code in the program header: SetConsoleOutputCP(65001);, then it fixes. but I think it's so troublesome to do this for each c++ program. What should I do?
I think this is my system's problem, the same code in Windows 7 is not a problem, I just want to find a more convenient solution instead of adding the same code to every file
There's the code:
#include <iostream>
#include <windows.h>
using namespace std;
int main()
{
SetConsoleOutputCP(65001);
cout << "文本" ; //Output will be garbled code if there's no line above
return 0;
}
The console in most operating systems only expects ASCII character input. In order to show some other char set you have to specify that in your code. The SetConsoleOutputCP command sets the "code page" windows should read from. By the way not all versions of windows have the same code for this command.
Please refer to the documentation found here.
The documentation suggests using EnumSystemCodePages to make sure the code for that language exists on that system.
P.S.
Your English is very good :)
EDIT
I tested your code on my computer with Visual Studio 2019 and got the following
Warning C4566 character represented by universal-character-name '\u6587' cannot be represented in the current code page (1255)
even with the SetConsoleOutputCP command you added. I assume you need to have chines installed for this to work. The problem is that I don't have the relevant code page for the windows console to look in for the char set. see this answer and this answer.
Alright, I'm a little bit (honestly way too) confused about how the heck I can make a program interact with another program.
For example, let's say a game, a shooter, when you run an external program and you make your character not able to die, or immediately shoot when detects an enemy, etc...
I was reading a little bit about it, and they say you have to know how the "target" is composed. But I still don't get it.
For example, let's say we've got a simple code like this:
#include <iostream>
#include <windows.h>
int main() {
for(int h = 0; ; h++) {
std::cout << "The H's value is: " << h << std::endl;
Sleep(1000);
}
return 0;
}
Then, how do I create another program where I can change the H's value to zero everytime I press any key?
Don't get me wrong, I ain't trying to hack anyone or anything, I'm just curious about how those programs work.
(Sorry if I've got some grammar issues, English isn't my native language).
Specific to your program in the exapmle if we take that the program is already compiled and you are not allowed to make any changes to the source code the solution would be to build a program which will run with high enough privileges to examine this process's memory and directly change the in-memory value of h, which should be on the top of the stack(or almost).
Speaking of some more "legal" ways to do so you should check you should read about inter process communication which can be done with multiple methods. Read this.
However most "Bots" and programs which help cheaters in games are in many cases graphics based and are able to analyse the image and thus help aim. On the other hand some "recoil reducers" simply move your mouse in the opposite direction of the recoil of the gun in game. So there is a ton of approaches to your question and for every particular case the answer might be different.
I am new in programming. but i know turbo C & i can work with it. But how to work on Dev C++?
i means 1.How to Compile & 2. How to Run. I have Windows so if anyone help me with proper example than it will be great.
Dev c++ is very simple! To do the basic, Open you file, compile and run using the menu Execute!
However, if u are starting something new now, I would suggest you consider using eclipse. It is not so easy in the first days but the long term gain is giant!
I would like to improve my answer... I suggested that you should consider using eclipse. I still think that eclipse is great. Furthermore, I had had some problems with the old version of dev c++. After reading the comment of #Orwell (which provided facts that I didn't know), I checked the new version and the issues that I had had before disappeared. So, the big picture of dev c++ is that it is a program that works well and it is very simple. There is a cost to start using eclipse!
Example:
#include <iostream>
using namespace std;
int fibonacci(int n){
if(n==1)return 0;
if(n==2)return 1;
if(n>=3)return fibonacci(n-1)+fibonacci(n-2);
}
int main(){
//
int n =10;
cout << "The element of the Fibonacci series is " << fibonacci(n) << "\n";
return 0;
}
I'm running a graphical program in Turbo C++ using DosBox on Windows 7 64 bit. Now, I want to use the IBM3514 graphics driver in the High resolution mode (IBM3514HI). So, I wrote the following bare bones program to test it:
#include <graphics.h>
#include <iostream.h>
void main() {
int gd = IBM3514, gm = IBM3514HI, e;
initgraph(&gd, &gm, "C:\\TC\\BGI");
if (e = graphresult()) {
cout << grapherrormsg(e);
}
cleardevice();
rectangle(100, 100, 300, 300);
cin.get();
closegraph();
restorecrtmode();
}
Now, the program compiles and runs without any errors. However, the initgraph function call doesn't initialize graphics mode. The return value of graphresult is 0. Hence, no error has occurred. Yet, the program still runs in text mode. The blinking underscore is visible and the rectangle is not drawn.
I checked my C:\TC\BGI folder and the IMB3514.BGI file exists. Thus I assume that it does load the graphics driver. Yet, I can't figure out why the program doesn't execute in graphics mode, or even throw an error. However it works perfectly fine if I use the default settings: int gd = DETECT, gm;
Any explanation as to why my program doesn't work will be greatly appreciated. Please try to provide a fix to this problem. I would really like to draw on a 1024x768 screen with 256 colors.
Under Windows your graphical adaptor is virtualized. You can't access it directly and use its specific features (unless you use DirectX/OpenGL/other strange methods). DOSBox emulates some "historical" graphical adaptors for the programs it runs (to be precise: Tandy/Hercules/CGA/EGA/VGA/VESA). You must use the VESA 2.0 driver of TC (or in general the VESA driver).
The correctly name of the driver is ibm8514.bgi - not "3514" and not "imb" or so. But like my previous speaker said, better you use another driver. The best choice is to use the egavga.bgi driver of the Turbo resp. Borland C++ or Turbo Pascal package. Then you should compile them successful.
Expect you need a special feature of this driver. Then you must check them of this effort if you need them. I think the egavga.bgi, vesa or a directly switch to the graphic mode with some special routines to make graphic should work in DOSBox, EmuDOS or in all 32-Bit-Version of Windows like Windows XP or so.
Try this code instead:
int gd = 6, gm = 0, e;
(Both variables are INTEGERS, not STRINGS)
I do some image processing work in C++. For this i use CImg.h library which i feel is good for my work.
Here is small piece of code written by me which just reads an image and displays it.
#include "../CImg.h"
#include "iostream"
using namespace std;
using namespace cimg_library;
int main(int argc,char**argv)
{
CImg<unsigned char> img(argv[1]);
img.display();
return 0;
}
When i give lena.pgm as input this code it displays the image. Where as if i give some other image, for example ddnl.pgm which i present in the same directory i get "Segmentation Fault".
When i ran the code using gdb i get the output as follows:
Program received signal SIGSEGV, Segmentation fault.
0x009823a3 in strlen () from /lib/libc.so.6
Missing separate debuginfos, use: debuginfo-install glibc-2.9-2.i686 libX11-1.1.4-5.fc10.i386 libXau-1.0.4-1.fc10.i386 libXdmcp-1.0.2-6.fc10.i386 libgcc-4.3.2-7.i386 libstdc++-4.3.2-7.i386 libxcb-1.1.91-5.fc10.i386
Can some one please tell me what the problem is? and how to solve it.
Thank you all
Segfault comes when you are trying to access memrory which you are not allowed to access.
So please check that out in the code.
The code itself looks just fine. I can suggest some ways to go ahead with debugging -
Try removing the display() call. Does the problem still occur? (I'd assume it does).
Try finding out where in the CImg code is the strlen() that causes the segmentation fault (by using a debugger). This may give additional hints.
If it is in the PGM file processing, maybe the provided PGM file is invalid in some way, and the library doesn't do error detection - try opening it in some other viewer, and saving it again (as PGM). If the new one works, comparing the two may reveal something.
Once you have more information, more can be said.
EDIT -
Looking at the extra information you provided, and consulting the code itself, it appears that CImg is failing when trying to check what kind of file you are opening.
The relevant line of code is -
if (!cimg::strcmp(ftype,"pnm")) load_pnm(filename);
This is the first time 'ftype' is used, which brings me to the conclusion that it has an invalid value.
'ftype' is being given a value just a few lines above -
const char *const ftype = cimg::file_type(0,filename);
The file_type() function itself tries to guess what file to open based on its header, probably because opening it based on the extension - failed. There is only one sane way for it to return an invalid value, which would later cause strcmp() to fail - when it fails to identify the file as anything it is familiar with, it returns NULL (0, actually).
So, I reiterate my suggestion that you try to verify that this is indeed a valid file. I can't point you at any tools that are capable of opening/saving PGM files, but I'm guessing a simple Google search would help. Try to open the file and re-save it as PGM.
Another "fun to track down" cause of segmentation faults is compilier mismatches between libraries - this is especially prevalent when using C++ libraries.
Things to check are:
Are you compiling with the same compiler as was used to compile the CImg library?
Are you using the same compiler flags?
Were there any defines that were set when compiling the library that you're not setting now?
Each of these has bitten me in subtle ways before.