how to read 2 bytes of a wav file each time and draw a waveform?

I try to read data from a wav file by using fread(). It works all fine when I read the header.But when it starts to read sample data, it will only reads 4 bytes each time. Following is my code

// header varibles
char    RIFF[4];
int     chunkSize;
char    WAVE[4];
char    fmt[4];
int     subChunk1Size;
int     audioFormat;
int     numChannels;
int     sampleRate;
int     byteRate;
int     blockAlign;
int     bitsPerSample;
char    data[4];
int     subChunk2Size;


FILE *wavFile;
string wavName;
cout << "Please type the name of the .wav file:";
cin >> wavName;
wavFile = fopen(wavName.c_str(),"r");
if(wavFile != NULL){
    cout << "good"<<endl;
    fread(RIFF, 4, 1, wavFile);
    fread(&chunkSize, 4, 1, wavFile);
    fread(WAVE, 4, 1, wavFile);
    fread(fmt, 4, 1, wavFile);
    fread(&subChunk1Size, 4, 1, wavFile);
    fread(&audioFormat, 2, 1, wavFile);
    fread(&numChannels, 2, 1, wavFile);
    fread(&sampleRate, 4, 1, wavFile);
    fread(&byteRate, 4, 1, wavFile);
    fread(&blockAlign, 2, 1, wavFile);
    fread(&bitsPerSample, 2, 1, wavFile);
    fread(data, 4, 1, wavFile);
    fread(&subChunk2Size, 4, 1, wavFile);
    int     samples[subChunk2Size/2];
    fread(samples, 2, subChunk2Size/2, wavFile);
}

I already know that bitsPerSample is 16 so I should read 2 bytes as one sample. But no matter what number I put in the last line, it reads 4 bytes of data.

Here is the first 16 bytes of sample data in hexadecimal

0000 0000 0000 0000 0900 1600 1600 1600

The correct out put should be:

0 0 0 0 9 22 22 22

My output is:

0    0    1441801    1441814

Also, I need to draw a waveform by using those data. How can I do it in c++? Do I need to import any library or using api? I am using Mac OS.

Please help. Thank you!