Using argc and argv data

Hi fellow programmers

I have been trying to figure out how to use the argc and argv data. I have a main function that looks like

Code:

int main(int argc, char *argv[])
{
   int num_roads = argc;
   char *road_data = &argv[1][0];
   int number_routes = num_routes(int num_roads, char *road_data);
   //other code goes here...

But then i have a few local functions that require the integer array that is being passed in the main function, argv and argc. I can't work out what the header for the local function should be..

Code:

int get_num_routes(int num_roads, char *road_data)
{
   int num_into = 0; /* Number of one way roads into the intersection */
   int num_routes = 0;

   for (i = 0; i < num_roads; i++)
   {
   if(road_data[i][0] == 0)
      num_into++;
   }
   printf("%3d\n", num_into);
   return 0;
}

and also can't work out how to call the data i need from argv and argc in this local function (that isn't close to being finished btw).

I am having a horrible time learning about using arrays and pointers. Have spent heaps of time reading up on it but need to start learning by doing and that isn't going great. Also it is a bit after 4am and my brain has turned off.

Hope this makes sense,

Thanks -Nick

Making the assumption that your command syntax is somthing like
program 20 33 64 23 40
then
argc = 6
argv[0] = "program"
argv[1] = "20"
...

So:

Code:

int param;         // used to loop thru argv
int values[20];    // to store the integers from argv
...
for (param= 1;     // start after the program string
     param< argc;  // loop until end of parameters
     param++)      // next parameter
{
    value[param-1] = atoi(argv[param]); // convert to int
}

Now you have an integer array created from the program's parameter list.

Thanks, that was just what i was looking for. However i have now run into an all new problem that I am having trouble dealing with.

Code:

#include <stdio.h>
#include <stdlib.h>

/* Prototypes of local functions */
int get_num_routes(int num_roads, int *road_type);

int main(int argc, char *argv[])
{

   int num_roads = argc - 1;
   /* To create an integer array from the input char array */
   int i;
   int road_type[num_roads];
   for(i = 0; i < num_roads; i++)
   {
      road_type[i] = atoi(argv[i+1]);
   }
   /* -----------------end road type thing-------------------*/
   int num_routes = get_num_routes(num_roads, *road_type);

   return 0;
   }


   /* Calculate the number of routes in this particular intersection */
int get_num_routes(int num_roads, int *road_type)
{
   int i, j;
   int num_into = 0; /* Number of one way roads into the intersection */
   int num_outof = 0; /* Number of one way roads out of the intersection */
   int num_routes = 0;
   for (i = 0; i < num_roads; i++)
   {
      if(road_type[i] == 0)
         num_into++;
      else if (road_type[i] == 1)
         num_outof++;
   }
   /* code to calculate num_routes value goes here */
   return num_routes;
}

This gives the problem:

Code:

23: warning: passing arg 2 of `get_num_routes' makes pointer from integer without a cast

If anyone has got any ideas about how to deal with this problem then i would be super grateful.

Cheers people,
-Nick

Code:

int num_routes = get_num_routes(num_roads, *road_type);

Remove the * from this function call. Passing the name of the array will in effect pass a pointer to the first element of the array.


Quzah.

Yay for Quzah

Cheers man,
-Nick