controlling contents of a linked list

greeting!

Just found a sample linked list program and I've decided to play around with it (hoping that I can incorporate it with the project I'm currently working on).

here is the code: (this is only a quick hack/modification on the sample program that I've found, I haven't fix the warning message yet)

Code:

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

typedef struct {
  char name[1000];
} data;

typedef struct {
  data  d;
  struct NODE *next;
} NODE;

#define CFG_FILE "Read.txt" // name of file to be open

int main(void)
{
  
int num = 0;
FILE *cfgfile;
char data[80];
int count = 1;		//display purposes

NODE* head = NULL;  // this should always point to the 1st node
NODE* pin = NULL;   // used to iterate through nodes. 


	cfgfile = fopen ( CFG_FILE, "r" ); // open file, simulate the data retrieve from the database
		if ( cfgfile == NULL )
		{
			perror ( "Error in reading text file containing cfg file location!!!" );
		}
		else
		{
			while ( fgets ( data, 80, cfgfile ) != NULL )  //delinmeter is newLine
			{
				printf("%d Line Read: %s",count++,data); // prints out the contents of Read.txt
					if( head == NULL )
					{
						head = (NODE*) malloc(sizeof(NODE));
						head->next = NULL;
						pin = head;
					}
					else {
						pin->next = (NODE*) malloc(sizeof(NODE));
						pin = pin->next;
						pin->next = NULL;
					}
				strcpy(pin->d.name,data);
			}
		fclose ( cfgfile );
		}


	//Printing the data. Goes through the linked list node by node.
	printf("\n\n");
	pin = head;
	while( pin != NULL )
	{
		printf("%s", &pin->d.name);
		num = num + strlen(pin->d.name);
		pin = pin->next;
	}
	printf("\ntotal size of string is %d\n",num);

	// cleanup
	while( head != NULL )
	{
		pin = head->next;
		free( head );
		head = pin;
	}

	return 0;
}

the question is, what would I have to do in order for the contents of a linked list to be place in one string (character array).
to elaborate more.
let say the content of the Read.text (which can vary )are as follows:

<DATA> 1
<DATA> 2
<DATA> 3
<DATA> 4

after reading the file and inserting the values to the linked list, how would I arranged the contents of the linked list into one string,
into this format

<DATA> 1<DATA> 2<DATA> 3<DATA> 4

any kind of help or comment will be much appreciated.

regards,
jaro

Code:

{
  char *temp, *str = NULL;
  int len = 0;
  NODE *n;

  for(n = head;n;n = n->next)
  {
    if(!(temp = realloc(str, len + strlen(n->data) + 1)))
    {
      puts("Memory allocation error!");
      // do whatever you need to do here when you're out of memory
    }
    else
    {
      str = temp;
      strcpy(str + len, n->data);
      len += strlen(n->data);
    }
  }
}

Don't forget to free() str when you're done with it.

Make another array and then just go to the beginnning of the linked list and put the string into the array with sprintf. Next loop through the list using strcat to add each string to the end.
~Sven

sprintf(), or better yet, strcat().

Thanks for all of your responses.
I now got an idea on how would approach this problem.

Will post back soon for the complete code or if I found some weird error.

-jaro

just finished working on the program.
Did some adjustment and add some extra function along the way.
Just want to hear some comment about the code and if I violate some coding rules.

here is the code:

Code:

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

typedef struct {
  char name[1000];
} data;

typedef struct sNODE *nodePtr;

typedef struct sNODE {
    data d;
    nodePtr next;
} NODE;


#define CFG_FILE "Read.txt" // name of file to be open
//make global
NODE* head = NULL;  // this should always point to the 1st node
NODE* pin = NULL;   // used to iterate through nodes. 


char* removeNewline(char line[])
{
	if (line[strlen(line)-1] == '\n')
	{
		line[strlen(line)-1] = '\0';
	}
	return line;
}



int stringLength(NODE* current) {
	int count = 0;
	current = head;
		while (current != NULL) {
			printf("%s", &current->d.name); // for display purpose only
			count = count + strlen(current->d.name);
			current = current->next;
		}
return count;
}


void linkCleanUp(NODE* last){
	while( head != NULL )
	{
		last = head->next;
		free( head );
		head = last;
	}
}



int main(void)
{
  
int strLen;
FILE *cfgfile;
char strdata[80];
int count = 1;		//display purposes
char *newstr;


	cfgfile = fopen ( CFG_FILE, "r" ); // open file, simulate the data retrieve from the database
		if ( cfgfile == NULL )
		{
			perror ( "Error in reading text file containing cfg file location!!!" );
		}
		else
		{
			while ( fgets ( strdata, 80, cfgfile ) != NULL )  //delinmeter is newLine
			{
				printf("%d Line Read: %s",count++,strdata); // prints out the contents of Read.txt
					if( head == NULL )
					{
						head = (NODE*) malloc(sizeof(NODE));
						head->next = NULL;
						pin = head;
					}
					else {
						pin->next = (NODE*) malloc(sizeof(NODE));
						pin = pin->next;
						pin->next = NULL;
					}
				strcpy(pin->d.name,strdata);
			}
		fclose ( cfgfile );
		}


	//Printing the data. Goes through the linked list node by node.
	printf("\n\n");
	strLen= stringLength(pin);
	printf("\ntotal size of string is %d\n",strLen);

	/* string them together.*/
	newstr = malloc(strLen + 1);
	newstr[0] = 0;
	pin = head;
		while (pin != NULL) {
			strcat(newstr, pin->d.name);
			removeNewline(newstr);
			pin = pin->next;
		}
	printf("\n======= Entire string: =======\n%s\n", newstr);
	free(newstr);

	// cleanup
	linkCleanUp(pin);

	return 0;
}

The content of the Read.txt remains the same.
output

1 Line Read: <DATA> 1
2 Line Read: <DATA> 2
3 Line Read: <DATA> 3
4 Line Read: <DATA> 4


<DATA> 1
<DATA> 2
<DATA> 3
<DATA> 4

total size of string is 36

======= Entire string: =======
<DATA> 1<DATA> 2<DATA> 3<DATA> 4

Forgot to mention on my first post that I'm using MVC6 under Win2K.

~jaro

removeNewline() doesn't have to return anything.

Your while loop in stringLength() could be replaced with a for loop (but of course either will work).

You read in a string into an 80-char buffer (data) and then copy it into d.data, a 1000-char buffer.

thanks for your comment dwks.

i'll try to make some changes regarding your suggestion.

-jaro