ftell error after the first call to fread

So I have a very simple program that reads the 3 first bytes of a file:

int main(void)

{

    FILE *fd = NULL;
    int i;
    unsigned char test = 0;
    fd = fopen("test.bmp", "r");

    printf("position: %ld\n", ftell(fd));

    for (i=0; i<3; i++) {
        fread(&test, sizeof (unsigned char), 1, fd);
        printf("position: %ld char:%X\n", ftell(fd), test);
    }

    return (0);
}

When I try it with a text file it works fine:

position: 0
position: 1 char: 61
position: 2 char: 62
position: 3 char: 63

but when I run it with a PNG for example I get:

position: 0
position: 147 char:89
position: 148 char:50
position: 149 char:4E

Note that the 3 first bytes of the file are indeed 89 50 4E but I don't know where the 147 comes from. With a bmp file I get:

position: 0
position: -1 char:42
position: 0 char:开发者_高级运维4D
position: 1 char:76

Do you know where these first positions come from? Thanks a lot for your help

You need to open the file in binary mode:

fd = fopen("test.bmp", "rb");

If you try to read a binary file like a bitmap in text mode, the bytes corresponding to carriage returns and linefeeds confuse things.

Please look at this question Reading bytes from bmp file.

Looks like problem is in the mode of opening it.

• check if the file exists in your developer/program directory
• check if the file is used by a other application
• try to copy the file under a second name, and open this file
• check the operating system: Windows use C:\Users\ , and Linux /home/user (you can see the differences ?
• check your code, if it for Windows use: C:\\Users\\you\\filename.ext
• check your file limit, increase it if all fails
• and last but not least, the the file pointer to the top of file (position: 0) with fseek(filehandle,SEEK_SET);