How to check for an event

SDL Development
1

Hi, wanted to know how to code for an error state in the following code. I am new to SDL. I simply want a true to some value if a window was successfully created. I’ve made this window generation a subroutine:

Code:

#include <SDL.h>
#include “make_Window.h”

void make_Window(int horizontal, int vertical) //SDL_Window *window)
{

SDL_Init(SDL_INIT_EVERYTHING);

// Create a Window in the middle of the screen
SDL_Window *window = 0;
window = SDL_CreateWindow(“Hello World!”,
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
horizontal, vertical,
SDL_WINDOW_SHOWN);
// Delay so that we can see the window appear
SDL_Delay(2000);

}

2

https://wiki.libsdl.org/SDL_CreateWindow

SDL_CreateWindow will return NULL if failed.

Not sure if that’s what you are asking.On Feb 13, 2017 8:15 AM, “speartip” wrote:

Hi, wanted to know how to code for an error state in the following code. I
am new to SDL. I simply want a true to some value if a window was
successfully created. I’ve made this window generation a subroutine:

Code:

#include
#include “make_Window.h”

void make_Window(int horizontal, int vertical) //SDL_Window *window)
{

SDL_Init(SDL_INIT_EVERYTHING);

// Create a Window in the middle of the screen
SDL_Window *window = 0;
window = SDL_CreateWindow(“Hello World!”,
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
horizontal, vertical,
SDL_WINDOW_SHOWN);
// Delay so that we can see the window appear
SDL_Delay(2000);

}

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3

Thats it. Thx!! I am just getting use to their library.

4

Well, a bit premature!

Code:

if (window == NULL) {
// In the case that the window could not be made…
printf(“Could not create window: %s\n”, SDL_GetError());
return 1;

I experienced problems with printf only to find out my IDE Eclipse is problematic with printf. After adding #include the printf was printing
the “Could not create window:” portion, but not the rest. Can anyone please tell me what is supposed to be printed after it : %s\n",SDL_GetError()
and how to get printf functional?

Thank you.

5

logically its working; in the braces within the printf is not functioning correctly.

6

I wanted to update, to focus the problem at hand and make sure nobody thought I was asking them to fix my compiler. No way!

This line initializes.

Code:

if (SDL_Init(SDL_INIT_EVERYTHING) == 0) {
printf(“SDL_Init failed: %s\n”, SDL_GetError());
return 1;}

Here I’ve purposely induced an error state by changing
Code:
(SDL_Init(SDL_INIT_EVERYTHING) != 0) to (SDL_Init(SDL_INIT_EVERYTHING) == 0)

The error is then thrown and 1/2 of the statement is printed from printf above see bold below:

SDL_Init failed: . But the other half of the statement isn’t printed.

But no value for
Code:
SDL,GetError()

is returned on the same line.

In short my printf statement is cut in half.

7

printf(“SDL_Init failed: %s\n”, SDL_GetError())

8

It doesn’t sound like you’ve actually induced an error state, but instead
are printing regardless of whether or not there is an error.

If there is not an actual error, you might expect SDL_GetError() to return
an empty string (not sure if that is specified by the API). So you would
see:

SDL_Init failed:

Because the %s was replaced by nothing.

Jonny DOn Wed, Feb 15, 2017 at 1:04 PM, speartip wrote:

printf(“SDL_Init failed: %s\n”, SDL_GetError())

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9

It will only print if
Code:
SDL_Init(SDL_INIT_EVERYTHING) == 0)

. But won’t print error info.
Program proceeds normally if I change it to:
Code:
SDL_Init(SDL_INIT_EVERYTHING) != 0)

It won’t print under just any circumstance.

10

sorry, in reply to this:

are printing regardless of whether or not there is an error.

11

Yes, but do you understand my point? There is no error to print, so
SDL_GetError() will not return an error message. Since there is no error,
go ahead and keep working on the rest of the program.

Jonny DOn Wed, Feb 15, 2017 at 4:07 PM, speartip wrote:

sorry, in reply to this:

are printing regardless of whether or not there is an error.

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12

There is no error to print, so SDL_GetError()

No, I got you. Thanks for your patience. I was just experimenting b/c I wanted to see some of the error codes produced, etc.

13

Oh, ad I wanted a code so I could make sure the printf function was working. Right now I just get 1/2 back:

printf(“SDL_Init failed: %s\n”, SDL_GetError())

That’s ok, I just want to make the code does work, and without an error hard to say.

But I’ve beat this topic up, so I am just going to move on here …

14

Well, you could use SDL_SetError() to at least show something.

https://wiki.libsdl.org/SDL_SetError

Jonny DOn Wednesday, February 15, 2017, speartip wrote:

Oh, ad I wanted a code so I could make sure the printf function was
working. Right now I just get 1/2 back:

printf(“SDL_Init failed: %s\n”, SDL_GetError())

That’s ok, I just want to make the code does work, and without an error
hard to say.

But I’ve beat this topic up, so I am just going to move on here …