Why is my .wav file not running?

Question

Without using structures, I'm trying to create a wave file that generates a tone at 900 Hz for five seconds. When I run it, however, it doesn't run or even give me the sample rate or the number of bytes. Here's my code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main () {
    FILE* fp;
    fp = fopen("sine.wav", "wb");
    if (fp == NULL) {
        printf("File does not exist.\n");
        return EXIT_FAILURE;
    }
    char ChunkID[4] = "RIFF", Format[4] = "WAVE", Subchunk1ID[4] = "fmt", Subchunk2ID[4] = "data";
    unsigned int ChunkSize, Subchunk1Size, Subchunk2Size;
    unsigned short int AudioFormat, NumChannels, BlockAlign, BitsPerSample;
    int SampleRate, ByteRate;
    Subchunk1Size = 16;
    AudioFormat = 1;
    NumChannels = 1;
    SampleRate = 44100;
    ByteRate = 2 * SampleRate;
    BitsPerSample = 16;
    BlockAlign = NumChannels * BitsPerSample / 8;
    Subchunk2Size = 10 * ByteRate;
    ChunkSize = Subchunk2Size + 41 - 8;
    fwrite(ChunkID, 4, 1, fp);
    fwrite(&ChunkSize, 4, 1, fp);
    fwrite(Format, 4, 1, fp);
    fwrite(Subchunk1ID, 4, 1, fp);
    fwrite(&Subchunk1Size, 4, 1, fp);
    fwrite(&AudioFormat, 2, 1, fp);
    fwrite(&NumChannels, 2, 1, fp);
    fwrite(&SampleRate, 4, 1, fp);
    fwrite(&ByteRate, 4, 1, fp);
    fwrite(&BlockAlign, 2, 1, fp);
    fwrite(&BitsPerSample, 2, 1, fp);
    fwrite(Subchunk2ID, 4, 1, fp);
    fwrite(&Subchunk2Size, 4, 1, fp);
    int i, amplitude = 37000;
    short int audio;
    float w, freq = 900 * 4;
    w = 2.0 * M_PI * freq;
    for(i = 0; i < 5 * SampleRate; i++) {
        if (i < 5 * SampleRate / 4)
            w = 900 * 4;
        else
            w = 0;
        w *= 2.0 * M_PI;
        audio = amplitude * sin(w * i / SampleRate);
        fwrite(&audio, 2, 1, fp);
    }
    fclose(fp);
    return EXIT_SUCCESS;
}

Answer 1

The most obvious problem is the Subchunk1ID which you have as "fmt".

That should be "fmt ", note the space at the end.