linked list and files...

[8ball]

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

typedef struct node nodeType; //data structure

struct node
{
  char name;
  nodeType *next;
};

//adds a new character in the linked list with each character read.
nodeType*
chinsert(nodeType* ptr,char c)
{
  nodeType *p;

  nodeType *new = (nodeType *)(malloc(sizeof(struct node))); //malloc to create the memory space that's needed to store the new character.
  new->name = c;
  new->next = NULL;

  if(ptr==NULL)
    return new;
  
  else
  {
    for(p=ptr; p->next!=NULL; p=p->next);
    
    p->next= new;

    return ptr;
  }
}

//When EOF is detected, traverse the linked list printing out the list of characters stored in the list
void
prnList(nodeType *ptr)
{
  nodeType *n = ptr;

  printf("\n");
  
  while(n != NULL)
  {
    printf("%c",n->name);
    n = n->next;
  }
  
  printf("\n");
  
}

//add underscore replacing space key
void
prn(nodeType *ptr)
{
  nodeType *n = ptr;

  while(n != NULL)
  {
    if(n->name == ' ')
      printf("%c",n->name='_');

    else
      printf("%c",n->name);

    n = n->next;
  }

  printf("\n");

}

//return any memory used back to the system before to the system before exiting program.
void
cleanUp(nodeType *ptr)
{
  nodeType *n;

  while(ptr->next != NULL)
  {
 
    n = ptr->next;
    ptr->next = n->next;
    free(n);
  }

   n = ptr;
   free(n);
}

int
main(int argc, char *argv[])
{
  char c;
  nodeType *ptr = NULL;

  while((c=getchar())!=EOF) //loop that reads in a character at a time, terminating the loop when it sees an EOF.
  {
    ptr = chinsert(ptr,c);
  }

  prnList(ptr);
  prn(ptr);
  cleanUp(ptr);

  return 0;
}

this program uses linked list to print the input replacing the space key with underscore.

how do i modify this program so it takes lines from a file?
do i just replace getchar with fgets?

[quzah]

Something like that. There are many ways to do it. The basic concept is:

open file
while not done
    read something from file
    process input
close file when done with it

If you're not sure, make a program for starters that just opens a file, reads a chunk (line, character, whatever) and displays that on the screen. The getchar replacement would be fgetc. fgets reads blocks of information, specificly strings or lines.

Quzah.

[8ball]

is it something like this?

void
prnL(nodeType *ptr)
{
  char c;
  FILE *fp=ptr;
  while (1){
    c=fgetc(fopen(argv[1],"r"));
    print("%c", fp)
      fp=fp->next;
  }
}

[quzah]

is it something like this?

void
prnL(nodeType *ptr)
{
  char c;
  FILE *fp=ptr;
  while (1){
    c=fgetc(fopen(argv[1],"r"));
    print("%c", fp)
      fp=fp->next;
  }
}

No. *cringe*

1) You don't assign a node pointer to a file pointer.
2) You don't call fopen every single time you read a character.
3) You don't advance file pointers like that. (I know, you're actually meaning to advance through your list, but it doesn't work that way...you can't just advance down a file.)

If you wanted to do what I'll guess you're trying to do here, it would be:

void
prnL(nodeType *ptr)
{
    int c;
    nodeType *node = ptr;
    FILE *fp=NULL;

    fp = fopen( argv[1], "r" );
    if( fp != NULL )
    {
        while( (c=fgetc( fp )) != EOF && node != NULL )
        {
            node->something = c; /* assign this character to an existing node */
            node = node->next;
        }
        fclose( fp );
}

And even that is not good code. I mean, I suppose it would work, but it's hardly good.

Quzah.