Thread: Newbie facing file management

Hi guys,
I approached the programming world only a week ago, so bear with me for the "stupidity" of my problem.

Code:

#include <stdio.h>
#include <stdlib.h>
#define M 100

main()
{
      char str[M],nomef[M];
      FILE *input;
      FILE *temp;
      FILE *output;
      char sep,check;
      int numpar=1,i;
      
      printf("Inserisci il separatore di stringhe:\n");
      scanf ("%c",&sep);

      printf("Inserisci il nome del file da aprire:\n");
      scanf ("%s",&nomef);

      input=fopen(nomef,"r");
      if (input==NULL) printf("Errore apertura file\n");

      temp=fopen("temp.txt","w+");
      if (temp==NULL) printf ("Errore creazione temp\n");
      check=getc(input);

      while (check!=EOF)
      {
            if(check==sep) 
            {putc ('\n',temp);
            numpar=numpar+1;}
            else putc(check,temp);
            check=getc(input);
            }     
                  fclose(input);
                  fflush(temp);

 for (i=0;i<numpar;i++) fscanf(temp,"%s",&str[i]);
      printf("%s",str[2]);
     
    
      system("PAUSE");
}

This code is supposed to create a string-array from a file formatted like so:

Code:

string#string1#string2#string3

Where '#' may by any user-given character. To create the array, I copied the content of the txt file in a temporary "temp.txt", replacing every istance of '#' with a '\n'. Then I used the fscanf procedure to copy the string from temp.txt to str[], using "numpar" as an indicator of how many strings are present in the files.
The code compiles and executes fine but if I try to access the 'str' array (with a printf procedure, as in the code I posted), the program crashes, and I really can't figure out why.
I tried using an external function, closing and opening the file (thinking that using "w+" or "r+" mode could lead to collaterals) and using the fgets procedure instead of fscanf, but with no result.
The temp.txt file is created, and its content are exactly what they should be, so I'm assuming that I either got something wrong with the fscanf, or I messed something up with the file management.
Thanks for helping out a "newbie" like me

Originally Posted by Adak

Nope.

stri[i] is now a pointer, not a char. Remove the & from the fscanf() line of code.

Unless you're going to malloc each strings row of chars for the 2D array, I don't see the point of counting the strings before hand. You could just process them.

Well, that sure is true...still the code compiled fine with the "&", I guess it is a little flexibile for newbies like me :P. Thanks for the heads up

This is an example of one way to do this, depending on what you want done with the comma (which I use here as the string separator).

Code:

#include <stdio.h>

int main(void) {
   FILE *fp;
   int i,r,c,ch;
   char str[100][100];
   char end=',';
   fp=fopen("Edelweiss.txt", "r");
   if(!fp) {
      fprintf(stderr, "Error: file not found or not opened!\n");
      return 1;
   }
   while((c=fgetc(fp)) != EOF) { //show the text in the file
      printf("%c", c);
   }
   rewind(fp);
   printf("\n\n"); 
   r=c=0;                    //now separate each string between the end char, into strings
   while((ch=fgetc(fp)) != EOF) {
      if(ch==end) {
         str[r][c]='\0'; //C's end of string char
         r++;
         c=0;
      }
      str[r][c++]=ch;
   }
   for(i=0;i<=r;i++)
      printf("%s\n",str[i]);

   fclose(fp);
   printf("\n\n");
   return 0;
}

This is the content of Edelweiss.txt, if you want to use it (it's full of comma's).

Edelweiss, edelweiss, every morning you greet me.
Small and white, clean and bright, you look happy to meet me.
Blossom of snow may you bloom and grow, bloom and grow forever.
Edelweiss, edelweiss, bless my homeland forever.

Edelweiss, edelweiss, every morning you greet me.
Small and white, clean and bright, you look happy to meet me
Blossom of snow, may you bloom and grow, bloom and grow forever.
Edelweiss, edelweiss, bless my homeland forever.

Thanks for the example, it was very useful, the program now works like a charm .

I hope it's not a problem if I use this thread to ask another question about a different code:

Code:

#include <stdio.h>
#include <stdlib.h>
#define M 300

int partedec(float f);                                                            /*dichiarazione funzioni*/
void ordinadec(float v[],int dim);


main()
{
      FILE *input;
      char nomefile[M];
      float array[M],gruppo1[M],gruppo2[M],gruppo3[M];
      
      printf("Inserici il nome del file:\n");
      scanf("%s", &nomefile);
      
      input=fopen(nomefile,"r");
      int i=0,numfloat=0;
      while((fscanf(input,"%f",&array[i]))!=EOF) i++;                           /*creazione array*/
      numfloat=i;                                                              
      printf ("Il vettore letto presenta %d elementi:\n",numfloat);
      for (i=0;i<numfloat;i++) printf("%.2f\n", array[i]);
      
      ordinadec(array,numfloat);
    
      printf("Il vettore ordinato e':\n");
      for(i=0;i<numfloat;i++)
      printf("%.2f\n",array[i]); 
      int j,p,k;
      j=0;k=0;p=0;
      for(i=0;i<numfloat;i++)
      {                                /*divides the array in three groups based on the decimal component of the float numbers*/
                             if (partedec(array[i])>=0 && partedec(array[i])<=39)         /*.00<=decimal part<=.39*/
                             {
                                                       gruppo1[j]=array[i];
                                                       j++;
                             }
                             if (partedec(array[i])>39 && partedec(array[i])<=69)         /*.39<decimal part<=.69*/
                             {
                                                       gruppo2[p]=array[i];
                                                       p++;
                             }
                             if (partedec(array[i])>69 && partedec(array[i])<=99)         /*.69<decimal part<=.99*/
                             {
                                                       gruppo3[k]=array[i];
                                                       k++;
                             }
      }
      
      printf ("Stampa per gruppi:\n");
      printf("-------------------");
      
      printf("Gruppo 1 (parte decimale compresa tra .00 e .39)\n");                       /*prints out the different groups*/
      for (i=0;i<j;i++) printf("%f\n",gruppo1[j]);
      
      printf("Gruppo 2 (parte decimale compresa tra .40 e .69)\n");
      for (i=0;i<p;i++) printf("%f\n",gruppo2[p]);
      
      printf("Gruppo 3 (parte decimale compresa tra .70 e .99)\n");
      for (i=0;i<k;i++) printf("%f\n",gruppo3[k]);
      system("PAUSE");
}
int partedec(float f)                                                            /*returns the decimal component of a float number*/
{ int dec;
  f=f*100;
  dec=f;
  do dec=dec-100;
  while (dec>=100);
  return(dec);
}
void ordinadec(float v[],int dim)                                                /*sort element by their decimal part*/
{
     int i, ordinato;
     float temp;
     
     ordinato=0;
     
     while(ordinato==0)
     {
                       ordinato=1;
                       for(i=1;i<dim;i++)
                       {
                                         if(partedec(v[i])<partedec(v[i-1]))
                                         {
                                                temp=v[i];
                                                v[i]=v[i-1];
                                                v[i-1]=temp;
                                                ordinato=0;
                                         }
                       }
     }
}

The code compiles and works fine, but the assignment "gruppo1[j]=array[i]" creates some problem:the numbers are plain wrong, gruppo1 and gruppo2 contains only 0.00 numbers, and gruppo3 contains some crazy random number. The number of elements in each 'gruppo' array is right. What did I mess up this time?
Thanks for helping out a newbie (again )

Check the array[i] contents, by printing it out, just before the assignments. Are the values there, OK?

Next, look at the if() statement to see if it's correct. Add a printf("* ") next to the assignment line of code, to check whether the assignment code is actually being executed.

Partedec() is returning good values?

Originally Posted by Adak

Check the array[i] contents, by printing it out, just before the assignments. Are the values there, OK?

Next, look at the if() statement to see if it's correct. Add a printf("* ") next to the assignment line of code, to check whether the assignment code is actually being executed.

Partedec() is returning good values?

The array[i] is printed just before, and the values are right. The if statement also seems to work fine, since the j,k and p counters reflects the right number of values (ie,if I have 3 float with the decimal part included between .00 and .39, the j counter will be equal to 3). The printf("*") next to the 3 assignments also returns a number of '*' equal to the numbers of elements of array[i].
The partedec() function also works, since it is used to sort the array by its decimal parts, and to be sure of it I also did a print cycle of partedec(array[i]), which returned the right values.

Error is in print statements. All three should be using i as the index, not j,p,or k.

Code:

      printf("Gruppo 1 (parte decimale compresa tra .00 e .39)\n");                       /*prints out the different groups*/
      for (i=0;i<j;i++) printf("%f\n",gruppo1[j]); //use gruppo1[i]


       
      printf("Gruppo 2 (parte decimale compresa tra .40 e .69)\n");
      for (i=0;i<p;i++) printf("%f\n",gruppo2[p]); //use i not p
       
      printf("Gruppo 3 (parte decimale compresa tra .70 e .99)\n");
      for (i=0;i<k;i++) printf("%f\n",gruppo3[k]);  //use i not k

Originally Posted by Adak

Error is in print statements. All three should be using i as the index, not j,p,or k.

Code:

      printf("Gruppo 1 (parte decimale compresa tra .00 e .39)\n");                       /*prints out the different groups*/
      for (i=0;i<j;i++) printf("%f\n",gruppo1[j]); //use gruppo1[i]


       
      printf("Gruppo 2 (parte decimale compresa tra .40 e .69)\n");
      for (i=0;i<p;i++) printf("%f\n",gruppo2[p]); //use i not p
       
      printf("Gruppo 3 (parte decimale compresa tra .70 e .99)\n");
      for (i=0;i<k;i++) printf("%f\n",gruppo3[k]);  //use i not k

That sure was a stupid mistake, thank you very much, again :P

Happens to us all, from time to time. You're welcome.