I have just started to learn C language and I'm just trying to write Hello World to get started but I get this error message. I'm sure the answer is obvious but can someone please tell me what I need to do? This is my code:
#include <stdio.h>
int main()
{
printf("Hello World ");
system("Pause");
return 0;
}
#include<stdlib.h>
Include this header file..
You need to add another header file:
#include <stdlib.h>
When you have an undefined call like this you can always throw "man 3 system" and you'll get something like this so you can see if you're missing a header file.
FYI, for your specific program, you may want to consider no using system("Pause") since it's system dependent. It would be better to pause with a break point (if you're using an IDE) or something more C standard like getchar()
You need to #include <stdlib.h>
If you aren't sure which header a standard function is defined in, its man page will tell you.
Insert
#include <stdlib.h> //in C
or
#include <cstdlib> //in C++
before your main() function.
Note that your IDE should refrain from closing your program. If it doesn't, change IDE.
You should include the following library.
#include <stdlib.h>
It's simple as that.
I hope you find this useful.
As the others said, you need to include an header; if you're running on Linux, you may install "manpages-dev" package, and then tape "man system" which will tell you what are the headers you need to use.
Related
I'm trying to use isspace and strlen in my code, so I used #include <ctype.h>. I'm getting the error: "In file included from" (doesn't say anything after 'from') on the #include <ctype.h> line. I'm using Netbeans and I was confused by Cygwin, so I may have made a mistake when I downloaded it. Any idea what the problem is and how I can fix it?
Also, #include <string.h> isn't giving me an error.
Thanks!
Note: This is TurboC++ so please don't expect STL
I have this simple code that have no other graphics.h functions rather than it's driver's declaration and call. I aim to:
Print a first string (A longer one)
Go to the first string's coordinates, clear that string (using clreol())
Print the second string which is shorter.
But I rather get this output on print of second string:
Shorter phrase.██████████████████████████████████████████████████████████████████
Here's my code:
#include <stdio.h>
#include <conio.h>
#include <graphics.h>
int gdriver=DETECT, gmode;
void main(){
clrscr();
initgraph(&gdriver,&gmode,"C:\\TURBOC3\\BGI");
printf("Longer phrase than next.");
getch();
gotoxy(1,1);
clreol();
printf("Shorter phrase.");
getch();
}
When I remove the initgraph() function, it works fine, so there might be the problem, but of course I need it.
Haha - coding problems from stoneage ;). Thanks for this - it activated some nice memories.
My guess would be that you run into problems because you are mixing BGI (graphics) functions and "normal" text output. Try replacing the text output calls with calls to the corresponding BGI functions (if I remember correctly, this was called outtextxy() or something).
My code worked perfectly for months until today. Its in C++
#include <iostream>
#include <cv.h>
#include <highgui.h>
#include <stdio.h>
using namespace std;
int main()
{
IplImage* img = cvLoadImage("C:/Users/Amadeus/Documents/H1/cat.png");
int result=cvSaveImage("C:/Users/Amadeus/Documents/H1/cat.png",img); <----- Problem
return 0;
}
It keeps saying "cvSaveImage was not declared in this scope". Files that would compile perfectly before all say it now. I don't understand why it worked for many months and today it says it wasn't declared. I even opened files that I knew worked for sure and even those didn't. It's like the header files are corrupt or something? What do you think?
Obviously, something changed in your system. I assume you don't know what exactly. The good point to start finding it out is to view your file after preprocessing is done. See for example this question on how to do this. Most probably you are pointing wrong or corrupted cv.h file for some reason.
By the way, why aren't you using modern C++ OpenCV functions imread and imwrite? They are in all ways better than their old C ancestors.
I realise there are a lot of questions related to this issue but I couldn't make head nor tale from the ones I read through.
I'm trying to start learning C for the Amiga and decided to have a try following this tutorial:
http://www.pcguru.plus.com/tutorial/amiga_c.html
On reaching this point, I'm already running into noob problems:
#include <proto/intuition.h>
#include <intuition/screens.h>
#include <proto/dos.h>
#include <stdio.h>
int main(void) {
struct Screen *myScreen;
if (myScreen = LockPubScreen(NULL)) {
printf("Public Screen locked.\n");
Delay(100);
UnlockPubScreen(NULL, myScreen);
printf("Public Screen unlocked.\n");
}
return 0;
}
I'm using the GCC compiler with the following command from the Shell:
gcc -o LockPubScreen LockPubScreen.c
This returns the following:
Warning: assignment makes pointer from integer without a cast
undefined reference to 'LockPubScreen'
undefined reference to 'Delay'
undefined reference to 'UnlockPubScreen
Apart from 'HelloWorld' this is the first attempt at either C or programming the Amiga so I imagine I missing something obvious.
You probably need to include one or more of these additional files to get the prototype for the functions you're missing:
#include <intuition/gadgetclass.h>
#include <intuition/IntuitionBase.h>
#include <libraries/gadtools.h>
#include <clib/exec_protos.h>
#include <clib/intuition_protos.h>
#include <clib/gadtools_protos.h>
Then, as NPE suggests, may may run into link errors if your compiler doesn't include the requisite library by default, and if you don't specify it.
If you had mentioned that you were trying to compile the program under AmigaOS 4.x, the answer would have been obvious. Library function calls in OS4 must either contain the library interface as well - IIntuition->LockPubScreen(), IDOS->Delay(), etc. - or you must #define __USE_INLINE__ at the beginning of the code.
I'm having some trouble with C standard functions. As an example, I'm getting that error in the memcpy function, even passing the right arguments to it.
I've included a header as #include "header.h", and I've included , and so in the "header.h" file.
(I'm also getting this error with strcpy, strtok, and some other standard functions, all respective headers included in "header.h")
Can anyone please help me with this? I'm running out of time to deploy this work...
Thanks in advance
It seems it was some trouble within eclipse. I right clicked one of those functions, selected Source->Add includes and it solved the problem (but didn't added any header).
I hope this can be helpful for someone else
Since you have not posted your code I assume that you have not included the following lines of code, at the top of your file:
#include <string.h>
In case your are using a C++ compiler (i.e. g++) then:
#include <cstring>