Problem while deleting multiple of fifth byte from a file with a single file pointer

Implementation detail is as follows:

1. Set the cursor in (5*i) position [i = 1 to n]
2. Read next 4 bytes
3. Set the cursor in (4*i) position [i = 1 to n]
4. Write the 4 bytes get from step 2.

    FILE* hFile = nullptr;
hFile = fopen("D:\\FifthByte.txt", "r+");
if (hFile)
{
    int readPos = 5;
    int writePos = 4;
    //find the file size
    fseek(hFile, 0, SEEK_END);
    int size = ftell(hFile);
    char szText[4];
    //set the cursor in fifth position
    fseek(hFile, readPos, SEEK_SET);
    while (size > readPos + 4)
    {
        fread(&szText, sizeof(char), 4, hFile); //read next four bytes
        readPos += 5;    //update the read position for next read
        fseek(hFile, writePos, SEEK_SET);  //Set the cursor for write
        fputs(szText, hFile);  //write the four bytes
        writePos += 4;    //update the write position for next write
        fseek(hFile, readPos, SEEK_SET);
    }
    fclose(hFile);
}

But the above code not working.
Content of my "D:\\FifthByte.txt" file is 

1234512345123451234512345123451234512345

After execution the content becomes 

12341234ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ(ÌÌ(4Ì(34ÌÌÌÌÌÌÌÌ(


Can anybody tell what is the problem with above code?