Read ints from a binary file that has 2560 numbers in it

Code:

---

#include <stdio.h>


int main(void)
{
    FILE *fp;
    int foo[10];
    int i;


    if ((fp = fopen("xyz.set", "rb")) == NULL) {
    puts("Error: Input file invalid");
    return -1;
    } else {
    for (i = 0; i < 10; i+=5) {
        fread(&foo[i], sizeof(int), 5, fp); 
    }
    }


    fclose(fp);


    for (i = 0; i < 10; i++) {
    printf("%d ", foo[i]);
    }
    putchar('\n');


    return 0;
}

---

I need to read in a file that has binary ints of 4 bytes (2560 total ints) each and i'm stuck with the above code. Any help will be appreciated. Thanks

Are the ints in machine-readable or human-readable format? If they've been dumped by fwrite and appear as garbage characters in a text editor, your approach should work if you read one at a time:

Code:

---

for (i = 0; i < 10; i++)
    fread(&foo[i], sizeof(int), 1, fp);

---

assuming that you wrote them the same way and endianness isn't an issue.

yup they appear as garbage characters in a text editor

This is the output that I get.

Is the size of ints on your machine 4 bytes?

Should you be using unsigned instead of signed ints?

Tim S.

i'm not entirely sure of that, so u think i should use buffersize instead ?

Quote:

---

Originally Posted by jackofalltrades

i'm not entirely sure of that, so u think i should use buffersize instead ?

---

I think you NEED to know something about the operating system and the compiler your are using!

You also need to know what format the binary data is in.
The format includes whether the data is signed or unsigned!

Tim S.

I haven't tested your code myself, but it looks fine to me. You could even replace the for loop with a single call to fread (assuming foo is large enough for 2560 ints):

Code:

---

fread(foo, sizeof(int), 2560, fp);

---

This will work only if the values in the file are in the same binary format (size and endianness) as the machine you're running on. You'll need to find out exactly what format the data is in before you can successfully read from the file.

I have got the code working, however i'm having issues with writing them to a file... does anyone have suggestions ?

Yes, I suggest you let us know how you're writing to a file so we can offer constructive criticism.

http://cboard.cprogramming.com/cplus...rite-file.html