Thread: Data not seeming to go to array

edit: fixed thanks

This line will overflow your buffer if the user types more than 39 characters:

Code:

scanf("%s", fname);

You can use this to be safer:

Code:

fgets( fname, sizeof( fname ), stdin );

Are you asking what's wrong with the code you have now or what else you need to write to make it work?
You're printing parts of the elements array even though you haven't written anything to the elements array...

Thanks for the tip on the buffer. I'd read a tutorial on it and had tried to implement it in this assignment however I think I got some parameters muddled up!

Anyway...
I assumed I had put things into the elements array and now I look back over it I realise that you are of course, correct.
I had tried to put things into the array by using

Code:

puts(elements[lcount]);

but I don't think this would work

so could I assign the data to an array by stating

Code:

int abundance_sorter()
{
  FILE *infile;
  char fname[40];
  char line[100];
  char elements[20][50];
  int lcount = 1;



  /* Read in the filename */
  printf("\nEnter the name the file you wish to open: ");
  fgets( fname, sizeof( fname ), stdin );


  /* Open the file.  If NULL is returned there was an error */
  if((infile = fopen(fname, "r")) == NULL) {
    printf("Error Opening File.\n");
    exit(1);
  }


  while(fgets(line, sizeof(line), infile) != NULL ) {
    /* Get each line from the infile */
	  printf("Line %d: %s", lcount, line);
          scanf("%c", &elements[lcount]);
	  lcount++;


	  //puts(elements[lcount]);




    /* print the line number and data */


  }
  printf("\nFile reading finished");
  printf("\n%d this is it", elements[2][5]);

  //printf("\n the value is %s", elements[2][1]);


  fclose(infile);  /* Close the file */
}

Edit: I've just inserted the

Code:

  fgets( fname, sizeof( fname ), stdin );

and it misses out the step where I should type in the filename and instead jumps to this output. :/

Enter the name the file you wish to open: Error Opening File.

unfortunately not :/

Edit: Just got it working... at least I think so

does this look correct?

Code:

  char line[100];
  char elements[20][50];
  int lcount = 1;
  char fname[0];



  /* Read in the filename */
  printf("\nEnter the name the file you wish to open: ");
  scanf("%s", fname);
  fgets( fname, sizeof( fname ), stdin );

Code:

  scanf("%s", fname);
  fgets( fname, sizeof( fname ), stdin );

choose one thing - do not use both

also note that fgets leaves the \n char in the buffer - youneed to remove it for example

Code:

char* p = strchr(fname, '\n');
if(p) *p = '\0';

Originally Posted by typhonius

Thanks for the tip on the buffer. I'd read a tutorial on it and had tried to implement it in this assignment however I think I got some parameters muddled up!

Anyway...
I assumed I had put things into the elements array and now I look back over it I realise that you are of course, correct.
I had tried to put things into the array by using

Code:

puts(elements[lcount]);

but I don't think this would work

No, puts() just prints the string you pass to it.
Try something like strcpy() or sscanf()

Originally Posted by typhonius

Edit: Just got it working... at least I think so

does this look correct?


Code:

Code:

  char line[100];
  char elements[20][50];
  int lcount = 1;
  char fname[0];



  /* Read in the filename */
  printf("\nEnter the name the file you wish to open: ");
  scanf("%s", fname);
  fgets( fname, sizeof( fname ), stdin );

Why are you creating an fname array that stores 0 characters? You need to give it a valid size.

Yeah, fname[0] was the problem. Also, I'd drop "abundance_sorter.h", and "element_info.h".
They're not needed, and don't add to the clarity of the program.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <ctype.h>
//#include "abundance_sorter.h"
//#include "element_info.h"
#define MAX 30


//int decision;
struct element {
  char name[40];
  int abun;
  //you can add wavelength or other data members here, easily. 
};


int main(void) {
   int i, decision;
   struct element ele[MAX];

	while(1)

	{
	printf("This program has the ability to do four tasks. "
			"\n\nPlease pick the corresponding number related"
			" to the task you wish to be done.\n\n"
			"1. Sort elements stored on file by either name or abundance.\n"
			"2. Find maxima from data on wavelengths and absorbances.\n"
			"3. Root Finding\n"
			"4. Element Database\n");

			scanf("%i", &decision);

		if (decision == 1)
		{
			printf("You have selected option 1");
			abundance_sorter();
			break;

		}
		if (decision == 2)
  		{
			printf("You have selected option 2");
			break;
		}
		if (decision == 3)
		{
			printf("You have selected option 3");
			break;
  		}
		if (decision == 4)
		{
			printf("You have selected option 4");
			element_info();
			break;
  		}
		else
		{
			printf("Invalid Number\n");
			continue;
		}
		
	}
   return 0;
}
/*
That is the main file and this is abundance_sorter.h
The code in comments is what has been tried yet proved detrimental to the program... ie, 
only outputting one line from the entire file etc.

Code:
*/
int abundance_sorter()
{
  FILE *infile;

  char line[100];
  char elements[20][50];
  int lcount = 1;
  char fname[30];



  /* Read in the filename */
  printf("\nEnter the name the file you wish to open: ");
  scanf("%s", fname);
  fgets( fname, sizeof( fname ), stdin );

  len = strlen(fname);     //removes the filename newline char
  fname[--len] = '\0';


  /* Open the file.  If NULL is returned there was an error */
  if((infile = fopen(fname, "r")) == NULL) {
    printf("Error Opening File.\n");
    exit(1);
  }


{
  while(fgets(line, sizeof(line), infile) != NULL ) {
    /* Get each line from the infile */
	  printf("Line %d: %s", lcount, line);
	  //scanf("%s", &elements[lcount]);


	  lcount++;


	  //puts(elements[lcount]);




    /* print the line number and data */


  }
}
  printf("\nFile reading finished");
  printf("\n%c this is it", elements[2][1]);

  //printf("\n the value is %s", elements[2][1]);


  fclose(infile);  /* Close the file */
  return 0; //    
}


//this is part 4, or element_info.h

//Code:

int element_info()
{

FILE *fp;
char infofilename[127], repeat[9], element[127], symbol[127];
int melt, answer;

   printf("\n\n[Please enter the filename:]\n\n");

      scanf("%s", infofilename);
      /* Try opening the file.*/
      fp = fopen(infofilename, "a"); /* If file exists, append data to end of file, else create new file...*/
      printf("Your file %s was created\n\n"
    		  "Now please enter the data you want stored"
    		  "\nElement: ", infofilename);
      scanf("%s", &element);
      fprintf(fp, "%s ", &element);

      printf("Symbol: ");
      scanf("%s", &symbol);
      fprintf(fp, "%s ", &symbol);

      printf("Melting Point: ");
      scanf("%d", &melt);
      fprintf(fp, "%d\n\n", melt);

      while(1)
      {
    	  printf("Would you like to enter more data?\n1. Yes\n2. No\n\n");
    	  scanf("%i", &answer);
    	  if(answer == 1)
    	  {
    	  printf("Please enter the data you want stored"
    	     		  "\nElement: ");
    	       scanf("%s", &element);
    	       fprintf(fp, "%s ", &element);

    	       printf("Symbol: ");
    	       scanf("%s", &symbol);
    	       fprintf(fp, "%s ", &symbol);

    	       printf("Melting Point: ");
    	       scanf("%d", &melt);
    	       fprintf(fp, "%d\n\n", melt);
    	       continue;
    	       }
    	  if(answer == 2)
    	  {
    		  printf("Thank you for exploiting me today");
    	  break;
    	  }
    	  else
    	  {
    		  printf("Invalid Number");
    		  continue;
    	  }

      }

      fclose(fp);

      return 0;
}

It now compiles, but is flawed in logic. I haven't run it yet, however.

your action selector could be improved

Code:

if (decision == 1)
{
 ...
}
if (decision == 2)
{
 ...
}
if (decision == 3)
{
   ...
}
if (decision == 4)
{
 ...
}

could be written as

Code:

if (decision == 1)
{
 ...
}
else if (decision == 2)
{
 ...
}
else if (decision == 3)
{
   ...
}
else if (decision == 4)
{
 ...
}

to avoid checking conditions father after the correct match was found
or using switch statement