Thread: Accessing elements in a struct

Hi all I have a struct defined as the following:

Code:

typedef struct command_struct {
      char name[BUFFSIZE];
      char *argv[ARRAYSIZE];
      int argc;
} command;

How do I go about accessing the *argv[ARRAYSIZE] data elements if I had a struct called command *cmds[ARRAYSIZE]?

Code:

void parse (char cmdline[], command *cmds)
{
  /* create a pointer to the command line */
  char * cmdline_ptr;
  cmdline_ptr = cmdline;

  char * cmd_name;
  cmd_name = cmds->name;

  char * cmd_argv;
  cmd_argv = cmds->name->argv;
/* ????? */
}

Thanks in advance.

#deinfe <string.h>
strlen(cmds->argv);

i think that answers your question

Actually misplaced, it doesn't. All I need to know is how to access that *argv[ARRAYSIZE] element in the command struct. I don't know what your code is doing. I want to create a pointer to that data element and that is what I was trying to do in my last set of instructions with:

Code:

command *cmds[ARRAYSIZE];
...
  char * cmd_argv;
  cmd_argv = cmds->name->argv;
...

But of course this does not access it at all. I just need a alternative to this. Thank you.

lol....after re-reading the original post i don't know where i got my answer from....

this is your first problem that i'm sure about:
cmd_argv = cmds->name->argv;

should be
cmd_argv = cmds->argv;

i could be wrong.....
but from there use

cmd_argv[x][y]
or
*cmd_argv[y]

don't get that stuck in your head until you know it works though

Misplaced, could you please help me out with this... obviously I am having some trouble with this but it's been such a long time since I've done C. Anyways, I want to read from the command line of a shell I am making and parse each individual word accordingly into each "word" into the argv array.
I have two problems: Number one, I am not sure if I am iterating correctly to place each value in each element of the argv. Number two, I am getting a seg fault when I am running the program below. Although of course, if we fix problem 1. number 2 should be no sweat.

Code:

...
#define BUFFSIZE 128
#define ARRAYSIZE 4
...
typedef struct command_struct {
      char name[BUFFSIZE];
      char *argv[ARRAYSIZE];
      int argc;
} command;
...
   command *cmds[ARRAYSIZE];
...

Code:

void parse (char cmdline[], command *cmds)
{
  /* create a pointer to the command line */
  char * cmdline_ptr;
  cmdline_ptr = cmdline;

  char * cmd_name;
  cmd_name = cmds->name;

  char * cmd_argv;
  cmd_argv = cmds->argv[ARRAYSIZE];

  while (*cmdline_ptr != '\0')
    /* while the cmdline_ptr is not equal to NULL */
    {
      /* write values to cmd->name and cmd->argv */
      while ((*cmdline_ptr != ' ') || (*cmdline_ptr != '\t')){
        *cmd_name++ = *cmdline_ptr;
        *cmd_argv++ = *cmdline_ptr++;
      }
    }
}

I don't use command line processing but you can try this:

#include <iostream>
using namespace std;

int main(int argc, char *argv[])
{
int i;
for(i = 0; i < argc; ++i)
cout << argv[i] << endl;
return 0;
}

compile and execute from the command line. I think each output will be a single word (that is, a single string) as I believe items in the command line are space separated, meaning that each "word" in the command line is interpretted as a separate string and read into argv individually.

//command line input
c:\ myProg.exe hello world

//expected output
myProg.exe
hello
world

i think he's right...
to the best of my recollection....
*argv[] is an array of string arrays
argc is the count of arguements

I know I know... but I wanted to do it a bit differently... oh well, I gues I am just going to have to go back to argc and argv the regular way. Thanks guys