Where is the segmentation fault? [closed]

Question

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Closed 7 years ago.

I know not everyone has used the PortAudio API, but maybe you can find it in here anyway.

#include <iostream>
#include <math.h>
#include "portaudio.h"

int main() {    
    PaDeviceIndex outputDevice;
    PaDeviceIndex deviceCount;
    outputDevice = Pa_GetDefaultOutputDevice();
    deviceCount = Pa_GetDeviceCount();
    const PaDeviceInfo * outputDeviceInfo;
    outputDeviceInfo = Pa_GetDeviceInfo(outputDevice);
    std::cout << "Name of default output device: " << outputDeviceInfo->name << std::endl;
    std::cout << "Struct version: " << outputDeviceInfo->structVersion << std::endl;
    return 0;
}

*EDIT: * sorry guys, I didn't know there even was a debugger. I wasn't trying to be rude or inconsiderate. It said it's caused by line 12 and 13, the ones that begin with std::cout. I don't see what the problem is.

Answer 1

Null pointer dereference. Pa_GetDeviceInfo is returning a null pointer.

Program received signal SIGSEGV, Segmentation fault.
0x080487f4 in main () at pa.cpp:12
12      std::cout << "Name of default output device: " << outputDeviceInfo->name << std::endl;
(gdb) print outputDeviceInfo
$1 = (const PaDeviceInfo *) 0x0

Answer 2

From the documentation:

const PaDeviceInfo* Pa_GetDeviceInfo ( PaDeviceIndex device )

Retrieve a pointer to a PaDeviceInfo structure containing information about the specified device.

Returns: A pointer to an immutable PaDeviceInfo structure. If the device parameter is out of range the function returns NULL.

You forgot to check for NULL before dereferencing the pointer. Oops.