GCC C编译错误，无法忽略void值，因为它应该是

Question

I'm having trouble compiling some C code. When I compile, I'l get this error:

player.c: In function ‘login’:  
player.c:54:17: error: void value not ignored as it ought to be

This is the code for the error:

static bool login(const char *username, const char *password) {
    sp_error err = sp_session_login(g_sess, username, password, remember_me);
    printf("Signing in...\n");
    if (SP_ERROR_OK != err) {
        printf("Could not signin\n");
        return 0;
    }
    return 1;
}

Any way to bypass this kind of error?
Thanks

Edit: All sp_ functions are from libspotify

Answer 1

It usually means you assign the return of a void function to something, which is of course an error.

In your case, I guess the sp_session_login function is a void one, hence the error.

Answer 2

Where is the error line exactly?

Without further information, I'm guessing it's here:

sp_error err = sp_session_login(g_sess, username, password, remember_me);

I guess sp_session_login is returning the void.

Try:

static bool login(const char *username, const char *password) {
    sp_session_login(g_sess, username, password, remember_me);
    printf("Signing in...\n");
    return 1;
}

Answer 3

我猜测sp_session_login被声明为返回void而不是sp_error并且有一些替代方法来确定它是否成功。

Answer 4

It doesn't look like sp_session_login actually returns anything. In particular, it doesn't return an sp_error , so there's no way this could work. You can't really bypass it.

Answer 5

You must declare void functions before use them. Try to put them before the main function or before their calls. There's one more action you can do: You can tell the compiler that you will use void functions.

For exemplo, there are two ways to make the same thing:

#include <stdio.h>

void showMsg(msg){
    printf("%s", msg);
}

int main(){
    showMsg("Learn c is easy!!!");
    return 0;
}

...and the other way:

#include <stdio.h>

void showMsg(msg); //Here, you told the compiller that you will use the void function showMsg.

int main(){
    showMsg("Learn c is easy!!!");
    return 0;
}

void showMsg(msg){
    printf("%s", msg);
}