Home arrow C and C+ arrow Writting to a File in C Language Using System Functions
Writting to a File in C Language Using System Functions PDF
Wednesday, 08 February 2012
The following example shows you how to write to a file using C system functions:

write_to_file.c
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>


struct packet {
    uint16_t source;
    uint16_t dest;
    uint16_t length;
    uint16_t checksum;
    char data[32];
};

typedef struct packet packet;

void write_packet(char *filename)
{
packet p;
int fd;

p.source=9080;
p.dest=22;
p.length=64;
p.checksum=1200;

strcpy(p.data, "ssh connection");


/*if(fd = open(filename, O_WRONLY) == 0) {
    printf("\nCannot open file.\n");
    exit(1);
    } */


fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0644 );

write(fd, &p.source ,2);
write(fd, &p.dest ,2);
write(fd, &p.length ,2);
write(fd, &p.checksum ,2);
write(fd, &p.data ,32);

close(fd);
}

int main(int argc, char *argv[])
{
write_packet("packet");
printf("\n");
return 0;
}


 
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