Unable to run graphics.h program in windows shell

Question

I'm trying to run this program on through gcc on Windows shell. GCC version that I'm using:

gcc (i686-posix-dwarf-rev0, Built by MinGW-W64 project) 8.1.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

The code:

#include<stdio.h>
#include<graphics.h>
int main(){
    int gd = DETECT, gm;
    initgraph(&gd, &gm, "");
    line(150,150,450,150);
    getch();
    closegraph();
}

At first, it was giving me this error:

fatal error: graphics.h: No such file or directory
     #include<graphics.h>

Then I added the graphics.h file to my gcc directory. But now it is showing this error:

Gph.C: In function 'int main()':
Gph.C:5:24: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
  initgraph(&gd, &gm, "");
                        ^
C:\Users\simple\AppData\Local\Temp\cchdXkih.o:Gph.C:(.text+0x2e): undefined reference to `initgraph'
C:\Users\simple\AppData\Local\Temp\cchdXkih.o:Gph.C:(.text+0x52): undefined reference to `line'
C:\Users\simple\AppData\Local\Temp\cchdXkih.o:Gph.C:(.text+0x63): undefined reference to `closegraph'
collect2.exe: error: ld returned 1 exit status

Can someone suggest an alternative way to run my program? I've already tried running it on Visual Studio and Online Compilers.

Answer 1

You can use CodeBlocks IDE for it. Link.

Or you can also use TurboC++ but you will have to make a minor change to your code:

#include<stdio.h>
#include<graphics.h>
int main(){
    int gd = DETECT, gm;
    initgraph(&gd, &gm, "C:\\TURBOC3\\BGI");
    line(150,150,450,150);
    getch();
    closegraph();
}

An advantage of using TurboC++ is that you will not have to download any extra files to run your graphics.h programs unlike other IDE like CodeBlocks or DevC++.

Answer 2

With respect to

fatal error: graphics.h: No such file or directory
     #include<graphics.h>

graphics.h is not a standard library. It refers in this case to the WinBGIm library that implements the Borland MS-DOS BGI API using the Windows GDI API.

Moreover header files in general are not libraries, which is why you get "undefined reference" errors - you have to link the library itself, not just include the header.

For:

Gph.C:5:24: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
  initgraph(&gd, &gm, "");

The warning is perhaps clear, but it is doubtful that you intended C++ compilation given that you tagged the question [C], but you have named your source with a .C instead of .c extension (lower-case). That causes C++ compilation as specified at https://gcc.gnu.org/onlinedocs/gcc/Overall-Options.html. The fact that the argument is not declared const in graphics.h is a problem of const-correctness where C is more permissive that C++. It is perhaps surprising the author has not fixed it. If you do use C++ compilation, then you would need to const_cast it.

So you need to:

• download the WInBGIm library,
• add the necessary include file path compiler switch (-I) to our build command
• add the necessary linker switches to your build command to link the library,
• change the filename extension to lower-case .c for C compilation.