Thread: Parsing a line and saving args

How about adding something like:

Code:

char **args = NULL;
int nargs = 0;

...inside the while() loop...
args = realloc(args, sizeof(char *)*(nargs+1));
args[nargs] = malloc(strlen(csh)+1);
strcpy(args[nargs], csh);
nargs++;

With the proper error checking of course

well, you don't *have* to store the individual tokens - you could simply write your command-processing function as it is, parsing each token as needed. otherwise, you could, for instance, create a two-dimensional array of chars to store each 'command' (making sure to keep track of the number of elements in use):

Code:

const int MAX_LINES = 1024, MAX_BUFF = 256;
char array[MAX_LINES][MAX_BUFF+1];
int i, size = 0;
csh = strtok(buffer, " ");
while(csh != NULL && size < MAX_LINES)
    {
      strncpy(array[size++], buffer, MAX_BUFF);
      csh = strtok(NULL, " ");
    }
for(i = 0; i < size; ++i) 
    {
      printf("array[%d] = '%s'.\n", i, array[i]);
    }

If somebody could do me a favore and explain to me what
Code:

char **args = NULL;


does, specifically the double **, I don't seem to recall learning that.

Thanks

its just another way of writing

Code:

char *args[]=NULL;

its a pointer to pointer of chars. or in the above code x arrays of ptr to chars. personal preference.

Unless I forgot how to count, the line numbers from the errors you posted don't match up with the source code you posted. I'm guessing the errors correspond to the realloc() and malloc() lines.

Which compiler are you using? You should only have to cast the return value of realloc() and malloc() with C++ (g++), not C (gcc).

The only message I get when I compile the code you posted with gcc is that main() doesn't return a value.

Originally Posted by itsme86

Unless I forgot how to count, the line numbers from the errors you posted don't match up with the source code you posted. I'm guessing the errors correspond to the realloc() and malloc() lines.

Which compiler are you using? You should only have to cast the return value of realloc() and malloc() with C++ (g++), not C (gcc).

The only message I get when I compile the code you posted with gcc is that main() doesn't return a value.

There are no errors in the code they've posted. Not so far as gcc is concerned. However, you will get a warning, compiling with -Wall:

Code:

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

main()
{
          char *cptr, *csh;
          char buffer[256];
          char **args = NULL;
          int nargs = 0;
          printf("sh%% ");
          cptr = fgets(buffer, 256, stdin);
          csh = strtok(buffer, " ");
          while(csh != NULL)
          {
                  args = realloc(args, sizeof(char *)*(nargs + 1));
                  args[nargs] = malloc(strlen(csh) + 1);
                  strcpy(args[nargs], csh);
                  nargs++;
                  csh = strtok(NULL, " ");
          }
}

	

		

			

			
				imain.c:6: warning: return type defaults to `int'
imain.c: In function `main':
imain.c:22: warning: control reaches end of non-void function
			
		
	

But that's to be expected, since it's obviously incorrect.

Quzah.

Originally Posted by pooty tang

Ah I see, sorry I was doing g++, now there are no errors with gcc.

Glad you figured it out.

Originally Posted by quzah

There are no errors in the code they've posted. Not so far as gcc is concerned. However, you will get a warning, compiling with -Wall:

That's what I said...

That's what I said...

Sure, but you didn't expect them to get it the first time they're told did you? I guess you've never read any of C+++C_Forever's posts...

Quzah.

Just use strcmp() with csh at the beginning the loop instead of using args[0]. That way their "bye" command doesn't get stored as a parameter.

By the way, args[0] will always be the first word they typed in, not the last.

Originally Posted by pooty tang

Ok I used the strcmp(csh, "bye") on the outer while loop but it does not exit the while loop when I type bye. It isn't recognizing that they are equal.

Leftover newline?
FAQ > How do I... (Level 1) > Get a line of text from the user/keyboard (C)
FAQ > How do I... (Level 1) > Comparing strings (C)