Question

I have a significant amount of data being generated in a C program. I want to write the data out into 1gb files.

How would I got about doing this?

At the moment, I go through a while loop (with a condition that will go on until 5 gbs data is created). It creates a struct and writes it to a file:

fwrite(storedVal, sizeof(keyEncode),1,fp);
//storedVal being the struct (which contains my data)

I would like each file to be called codes1, codes2 and increment on until the while loop is finished. I am sure it would include an if statement based on the size of the current file it is writing to. Then when it reaches 1gb, it begins on a new file.

edit //

actually it should be some sort of while statement , that keeps writting to the size, untill the file reaches 1gb and starts on the new one

My file at the moment is opened prior to my while loop:

fp = fopen("keys.dat", "wb");
while(condition is true) {
    //create a new struct with data and
    fwrite(storedVal, sizeof(keyEncode),1,fp);
}

Answer 1

Something along the lines of the following – note that there are some parts left out to fill in.

int write_count = 0;
int file_idx = 1;
FILE *fp;
char filename[20];

sprintf( filename, "codes%d", file_idx );
file_idx++;
fp = fopen(filename, "wb");

while( foo ) {

    //update data

    if( write_count + sizeof(keyEncode) > ONE_GIGABYTE ) {
        fclose(fp);
        write_count = 0;
        sprintf( filename, "codes%d", file_idx );
        file_idx++;
        fp = fopen(filename, "wb");
    }

    fwrite(storedVal, sizeof(keyEncode),1,fp);
    write_count += sizeof(keyEncode);
}

fclose(fp);

Update

You could incorporate logic like this into a helper function to write, as per Aaron’s response. Note that you would have to make some of the data members global and it would not be thread safe.