count the number occurance from text file for C program

[machi]

I’m the beginner to write the C program. Always got the error on output. Anyone can help. The program is open and read the text file. Then count all the number occurrence.
File format like this
21 43 32
32 32 21
43 5 6…


The code as below

#include <stdio.h>
#include <stdlib.h>
#define SIZE 0
int main ()
{
    int number1[SIZE], number2[SIZE];
    int i, j;
    int count;
    int n;
    char filename[40] ;
    FILE *fp;
printf("Enter file name: ");
    gets( filename );
    fp = fopen( filename, "r" );
    if ( fp == NULL )
    {
        printf("Cannot open %s for reading \n", filename );
        exit(1);      /* terminate program */
}
   n = fgetc( fp ) ;
    while (  n != EOF )
    {
    for (i=0; i<n; i++)
    {
        count=0;
        for (j=0; j<n; j++)
        {
            if (number1[j] == number1[i])
            {
                count++;
                }
            }
        number2[i] = count;
         }
    printf ("\n\n");
    for (i=0; i<n; i++)
       {
        printf ("Number %d: occurance %d times(s)\n", number1[i], number2[i]);
    }
 fclose( fp );
    return 0;
}
}

[qny]

Why SIZE 0? ???!?!?!?!???

You cannot have an array with size 0.
Turn on your compiler warnings and mind the warnings.

[Matticus]

Problems to correct before fixing your logic:

- You've defined "SIZE" to be zero, so your "number1" and "number2" arrays have zero indices.
- You read a character from the file once, then enter a while loop where 'n' doesn't change. You probably want "while((n=fgetc(fp)) != EOF)".
- And I don't think you want to be reading characters, you want to read integers. Consider "fscanf()" as one possibility.
- Don't use "gets()" as it is unsafe - use "fgets()" instead. FAQ > Why gets() is bad / Buffer Overflows - Cprogramming.com
- You show good intentions to use proper indentation, but it gets funky in some spots. As a result, you miss that the "while()" closing brace is in the wrong place (it is at the end of "main()").

---

Now, it appears that this program was written all in one go, compiled, and didn't work. That's not how to do it. Take it one step at a time.

First, write a program that opens the file, loads numbers into the array, and prints the arrays.

When you have this working, then begin developing the logic to accomplish the task.

I recommend reading this: A development process

[machi]

Modified the code as below. Seem it still can't read the file. Anyone can help. Thanks

#include <stdio.h>
#include <stdlib.h>
#define SIZE 20

int main ()
{
    int number1[SIZE], number2[SIZE];
    int i, j;
    int count;
    int n=10;
    FILE *fp;
    
   char filename[40] ;
   printf("Enter file name: ");
    gets( filename );
    fp = fopen( filename, "r" );
    if ( fp == NULL )
    {
        printf("Cannot open %s for reading \n", filename );
        exit(1);      /* terminate program */  
}
    
   fscanf(fp,"%d",&count);
  
        for (i=0; i<n; i++)
    {
        printf ("%d ", number1[i]);
    }

    for (i=0; i<n; i++)
    {
        count=0;

        for (j=0; j<n; j++)
        {
            if (number1[j] == number1[i])
            {
                count++;
            }
        }

        number2[i] = count;
    }

    printf ("\n\n");

    for (i=0; i<n; i++)
    {
        printf ("Number %d: %d occurencese\n", number1[i], number2[i]);
    }
 fclose(fp);
    return 0;
}

[Adak]

How many times are you trying to read data from the file?

Only once.

You need to fscanf() inside the loop, as well as the initial fscanf() outside the loop (which you have in place).

If you aren't going to use "count" after you read it from the file, I think that's probably wrong. <n should be <count shouldn't it?