reading a text file into a structure

问题

my text file is like this (the data in the file can also increase)

    822
    172.28.6.56
    172.34.34.53
    3244
    5434

    844
    192.150.160.145
    192.67.45.123
    2344
    234


    700
    192.13.56.6
    192.89.95.3
    4356
    3566

    522
    172.28.6.137
    172.28.6.110
    2543
    5245

    900
    255.255.255.255
    244.244.244.244
    2435
    3245

and my structure is like this

    struct input_par
    {
    int key_node;
    char src_ip[15];
    char dst_ip[15];
    int src_port;
    int dst_port;
    };

i have to fill this struture from data stored in file, once it completes inputting the 5 memebers of the structure i have to send this structure to a function i.e, i fill the structure with

    822
    172.28.6.56
    172.34.34.53
    3244
    5434

then i send this structure to a function, after sending it to a function i should again input the structure with the next data in the file i.e

    844
    192.150.160.145
    192.67.45.123
    2344
    234

I have to keep doing this till i reach EOF. I used fscanf it is not working properly how to do this? pls help

回答1:

As long as there is actually just one space between each of these structures... I might do something like this. It's pretty ugly, but would get the job done as long as you know your max line size for sure and the file structure doesn't have any hiccups (extra blank lines, etc). Otherwise you'd be better off writing much better code that handles and breaks/returns in case of exceptions.

As the comments note, you'll want to make sure to increase your char array's to account for the '\n' at the end. Here's some modifications to what I originally posted. Note, this may break if the line endings are Windows based (I believe). I added a little hack to try to correct the issue of array space and \n characters.

struct input_par
{
int key_node;
char src_ip[21];
char dst_ip[21];
int src_port;
int dst_port;
};


FILE* file = fopen("inputfile.txt", "r");
char linebuffer[21]; //a little extra room here than needed, presumably...
struct input_par ip;
int i = 0, l = 0;

while(fgets(linebuffer, 20, file))
{
   ip.key_node = atoi(linebuffer);
   fgets(linebuffer, 20, file);
   strcpy(ip.src_ip, linebuffer);

   l = strlen(linebuffer);
   for(i = 0; i < l; ++i){
      if(linebuffer[i] == '\n'){
         linebuffer[i] = '\0'
         break;
      }
   }

   fgets(linebuffer, 20, file);
   strcpy(ip.dest_ip, linebuffer);

   l = strlen(linebuffer);
   for(i = 0; i < l; ++i){
      if(linebuffer[i] == '\n'){
         linebuffer[i] = '\0'
         break;
      }
   }

   fgets(linebuffer, 20, file);
   ip.src_port = atoi(linebuffer);
   fgets(linebuffer, 20, file);
   ip.dst_port = atoi(linebuffer);
   fgets(linebuffer, 20, file); //get the empty line
}

回答2:

You can read the entire structure in one call to fscanf

--->

while(!feof(fp))
{
    input_par ip;
    int ret = fscanf(fp,"%*[ \t\n]%d%*[ \t\n]%s%*[ \t\n]%s%*[ \t\n]%d%*[ \t\n]%d",&ip.key_node,&ip.src_ip,&ip.dst_ip,&ip.src_port,&ip.dst_port);
    if (ret !=5)
    {
        //skip this record
        continue;
    }
    //process record ip
}

来源：https://stackoverflow.com/questions/6014045/reading-a-text-file-into-a-structure

标签

file-io

structure