Skipping to a new line in an input file.

I'm not sure how this may be done.
I've tried checking the FAQ, Getting a number or a string from the user, etc, can't quet figure it out.

I know the exact format of the input file, and I want to read in the first 6 columns only. ie:

Code:

month  1    3  4  5    6     77   8   99 
day       2   5  5  66   7    7     7   0

I have a structture for the 1st 6 columns:

Code:

struct EDFSection
{
	char Param[20];
	char Label[3], SFactor[4], SigBits[2];
	int Bit30, Bit31;
};

I only want to fill the structure and then move on to the next row.
desired output:

Code:

month  1    3  4  5    6     
day       2   5  5  66   7

It's a text input file.

1. Read in entire lines of data from the file into a buffer using the fgets function.
2. Use the sscanf function to just parse the first six fields from the line you just read in.
3. Repeat as necessary.

That was a good idea, why can't I think of things like this.
However, I haven't been able to make it work perfectly.
This is what I have:

Code:

for (j=0; j<nExpected; j++)
	{
		for (i=0; i<8; i++)
		{
			GetWord(inp, Temp[i]);
            SkipWS(inp);
		}

		strcpy(Sec.Param, Temp[0]);
		Sec.Label = atoi(Temp[1]);
		Sec.SFactor = atoi(Temp[2]);
		Sec.SigBits = atoi(Temp[3]);
		Sec.Bit31 = atoi(Temp[4]);
		Sec.Bit30 = atoi(Temp[5]);
		
	}

But given input:

Code:

late 1 2 3 4 5 6 7 
busy 1 2 3 4 5 6 7 
good 1 2 3 4 5  
ugly 1 2 3 4 5

It doesn't know not to stop reading at \n. I know I don't check for it, but I have to skip the whitespace after each entry to read the next. That's what SkipWS function is. GetWord scans a character at a time until isspace() is true.
**Temp is a 2D array, array of strings.
I can't figure out a better way to set up the logic here.

Code:

#include <stdio.h>

struct EDFSection
{
   char Param[20];
   int Label, SFactor, SigBits, Bit30, Bit31;
};

int main()
{
   static const char filename[] = "file.txt";
   FILE *file = fopen(filename, "r");
   if ( file != NULL )
   {
      char line[80];
      while ( fgets(line, sizeof line, file) != NULL )
      {
         struct EDFSection Sec;
         if ( sscanf(line, "%s %d %d %d %d %d", Sec.Param, &Sec.Label,
                     &Sec.SFactor, &Sec.SigBits, &Sec.Bit30, &Sec.Bit31) == 6 )
         {
            printf("Sec.Param   = %s\n", Sec.Param);
            printf("Sec.Label   = %d\n", Sec.Label);
            printf("Sec.SFactor = %d\n", Sec.SFactor);
            printf("Sec.SigBits = %d\n", Sec.SigBits);
            printf("Sec.Bit30   = %d\n", Sec.Bit30);
            printf("Sec.Bit31   = %d\n", Sec.Bit31);
            putchar('\n');
         }
      }
      fclose(file);
   }
   return 0;
}

/* my output
section.Param   = month
section.Label   = 1
section.SFactor = 3
section.SigBits = 4
section.Bit30   = 5
section.Bit31   = 6

section.Param   = day
section.Label   = 2
section.SFactor = 5
section.SigBits = 5
section.Bit30   = 66
section.Bit31   = 7
*/

while ( fgets(line, sizeof line, file) != NULL )
{
struct EDFSection Sec;
if ( sscanf(line, "%s %d %d %d %d %d", Sec.Param, &Sec.Label,
&Sec.SFactor, &Sec.SigBits, &Sec.Bit30, &Sec.Bit31) == 6 )

OK.
would fgets return false or NULL if there aren't 80 chars available? I don't quet see that.
and I would like the loop to stop at te end of the section marked by 'ENDL' and not copy the lines beginning with END.
I tried

Code:

while ( fgets(line, sizeof line, inp) != NULL )
	{
		if (strncmp(line, "ENDL", 4))
			break;

		if (!strncmp(line, "END", 3))
		{
			if ( sscanf(line, "%s %d %d %d %d %d", Sec.Param, &Sec.Label,
                     &Sec.SFactor, &Sec.SigBits, &Sec.Bit30, &Sec.Bit31) == 6)
			{
				printf("Sec.Param   = %s\n", Sec.Param);
                printf("Sec.Label   = %d\n", Sec.Label);

but it doesn't like it.
it exits the loop right away.

Code:

      while ( fgets(line, sizeof line, file) != NULL )
      {
         struct EDFSection Sec;
         if ( strncmp(line, "ENDL", 4) == 0 )
         {
            break;
         }
         if ( strncmp(line, "END", 3) != 0 &&
              sscanf(line, "%s %d %d %d %d %d", Sec.Param, &Sec.Label,
                     &Sec.SFactor, &Sec.SigBits, &Sec.Bit30, &Sec.Bit31) == 6 )
         {
            /* printing */
         }
      }
      fclose(file);

http://www.rt.com/man/fgets.3.html

but it doesn't like it.
it exits the loop right away.

Well of course it does, silly!

Code:

if (strncmp(line, "ENDL", 4))
			break;

Notice anything missing here?!


Quzah.

I thought

Code:

strncmp(line, "ENDL", 4)

returns a 1 when the strings are the same. Never mind then.

Instead of printing out the structure every time I scan it, I want to store then in an array of structures. So I'd pass the pointer to the array to a function that will read in all the individual structures. I don't really get how it is explained here:

Code:

struct Node *make_node ( void )
{
  struct Node new_node = malloc ( sizeof *new_node );

  /* Error check and set a default state */

  return new_node;
}

That's from Prelude's FAQ again.

I did it like it makes sense to me:

Code:

int 
main (void)
{
	int i, j, nExpected, nActual=0;
	char Word[25]; 
	FILE* inp;
	struct EDFLine *Sec;
..........................
Sec = calloc(nExpected, sizeof (struct EDFLine));

	ReadSection(inp, Sec, nExpected, &nActual);
}

int ReadSection(FILE * inp, struct EDFLine Sec[], int nExpected, int*nActual)
{
	char line[80];
	int  i=0;

	while ( fgets(line, sizeof line, inp) != NULL )
	{
		if ( strncmp(line, "ENDL", 4) == 0 )
		{
            break;
         }

		if (strncmp(line, "END", 3) != 0)
		{
			if ( sscanf(line, "%s %d %d %d %d %d", Sec[i].Param, &Sec[i].Label,
                     &Sec[i].SFactor, &Sec[i].SigBits, &Sec[i].Bit30, &Sec[i].Bit31) == 6)
			{
				nActual ++;
				i++;
			}
		}
		
	}

	if (*nActual == nExpected)
		return 1;
	else 
		return 0;
}

Right now it exits the loop right away, again.

Oh, and you guys told me numerously before not to typecast the calloc and never worked for me before. It kept giving me an incompatibility error, but now it worked.....

Oh, and you guys told me numerously before not to typecast the calloc and never worked for me before. It kept giving me an incompatibility error,

That's because you were compiling as C++ instead of C.


Quzah.

That's because you were compiling as C++ instead of C.

I tried even as C. But I guess there were other problems.

Originally Posted by earth_angel

Instead of printing out the structure every time I scan it, I want to store then in an array of structures.

How about something along this line?

Code:

size_t EDFread(const char *filename, struct EDFSection Sec[], size_t size)
{
   size_t i = 0;
   FILE *file = fopen(filename, "r");
   if ( file != NULL )
   {
      char line[80];
      while ( fgets(line, sizeof line, file) != NULL )
      {
         static const char stop[] = "ENDL", ignore[] = "END";
         if ( strncmp(line, stop, sizeof stop - 1) == 0 )
         {
            break;
         }
         if ( strncmp(line, ignore, sizeof ignore - 1) != 0 &&
              sscanf(line, "%s %d %d %d %d %d", Sec[i].Param,
                     &Sec[i].Label, &Sec[i].SFactor, &Sec[i].SigBits,
                     &Sec[i].Bit30, &Sec[i].Bit31) == 6 )
         {
            if ( ++i >= size )
            {
               break;
            }
         }
      }
      fclose(file);
   }
   return i;
}

int main()
{
   struct EDFSection section[10];
   size_t size = EDFread("file.txt", section, sizeof section / sizeof *section);
   /* ... */
   return 0;
}

struct EDFSection section[10];

That works, but the size of the array is not always 10. I have to dynamically allocate memory. So I end up passing to the function a pointer to an array of structures dynamically allocated. That's where the problems begin. I'm not sure how to arrange that.

What is size_t?

Originally Posted by earth_angel

That works, but the size of the array is not always 10. I have to dynamically allocate memory. So I end up passing to the function a pointer to an array of structures dynamically allocated. That's where the problems begin. I'm not sure how to arrange that.

Code:

int main()
{
   size_t size = 10;
   struct EDFSection *section = malloc(size * sizeof *section);
   if ( section )
   {
      size_t count = EDFread("file.txt", section, size);
      /* ... */
      free(section);
   }
   return 0;
}

Originally Posted by earth_angel

What is size_t?

An unsigned integral type suited for array indexing.

Code:

int ReadSection(FILE * inp, struct EDFLine Sec[], int nExpected)
{
.............................

if ( sscanf(line, "%s %d %d %d %d %d", Sec[i].Param, &Sec[i].Label,
                     &Sec[i].SFactor, &Sec[i].SigBits, &Sec[i].Bit30, &Sec[i].Bit31) == 6)
			{
				if ( ++i >= nExpected )
				{
					break;
				}

			}
		}
		print_Struct(Sec[i]);
		printf("\n\n");

............................

in the main then:

Code:

int 
main (void)
{
	int i, j, nExpected, nActual=0;
	char Word[25]; 
	FILE* inp;
	struct EDFLine *Sec;

................

nExpected = atoi(Word);   // Number of parameters expected

	SkipWS(inp);

	Sec = malloc(nExpected * sizeof *Sec);

	if (Sec)
	{
		nActual = ReadSection(inp, Sec, nExpected);
		free(Sec);
	}

..............

It's a bit different from yours Dave. It goes through the loop, but when I try to print the contects of Sec[i], I get gibrish.
Is the pointer refference wrong?

Print the structure after a line is successfully read and before you increment the index.