SDL_Init() fails without returning an error?

Question

When I try to execute this SDL3 program:

// g++ -Wall -Ofast main.cpp -Iinclude -Iinclude/SDL3 -Linclude/SDL3 -lSDL3 -o build/program
#define SDL_MAIN_HANDLED
#include <iostream>
#include <SDL3/SDL_main.h>
#include <SDL3/SDL.h>

int main(int argc, char* argv[]) {
    if (SDL_Init(SDL_INIT_VIDEO) != 0) {
        SDL_Log("SDL_Init failed: %s", SDL_GetError());
        return -1;
    }

    return 0;
}

... I get the following error:

SDL_Init failed:

(Note: SDL_GetError() doesn't return anything).

I'm using Windows 10 Pro.

Under SDL2 SDL_Init returns != 0 as error, since SDL3 returns true on success. You want if(!SDL_Init(SDL_INIT_VIDEOS)) — rafix07
– rafix07, Commented May 24 at 10:39
It is preferable to return SDL_APP_CONTINUE instead of 0 in case the actual order of the SDL_AppResult enums change. — cup
– cup, Commented May 24 at 10:49
@cup please add an Answer with a link to the official docs or news/discussion for that! — ti7
– ti7, Commented May 24 at 11:13
@cup That only applies to using the new (optional) main callbacks feature; defining main manually works as it used to (note how it returns int and not SDL_AppResult). On a related note, avoid defining SDL_MAIN_HANDLED unless you actually know what that entails! — val - disappointed in SE
– val - disappointed in SE, Commented May 25 at 1:21

wohlstad · Accepted Answer · 2025-05-25 13:46:06Z

25

There was a change in the API between SDL2 and SDL3.

In SDL2, SDL_Init returns an int which is:

0 on success or a negative error code on failure;

But in SDL3, SDL_Init returns a bool which is:

true on success or false on failure;

I.e. 0 means success in SDL2 but failure in SDL3.

Since you are using SDL3 your call to SDL_Init (which returned a value != 0), actually succeeded.

You should change the calling code to:

//--v---------------------------
if (!SDL_Init(SDL_INIT_VIDEO)) {
     SDL_Log("SDL_Init failed: %s", SDL_GetError());
     return -1;
}

(or compare explicitly against false if you prefer that style).

edited May 25 at 13:46

answered May 24 at 10:44

wohlstad

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