Problem with pointers

**grifan526** · 01-23-2010

I must write a program that reads in a file of ints into an array and lets the user choose the array index he wants to see. I can read in the file but when assigning it to an array value I obviously screwed up somewhere because it doesn't work, so here is my code for the main function and the function I am having problems in.

Code:

#include "my.h"

int main(int argc, char* argv[]){
FILE *fpIn;
int *arr;
int lim=0;
int j=0;


  if(openFiles(&fpIn,argv)){
     lim=getInput (&fpIn, &arr);
     oddEvenSort(arr,lim);
 do{
printf("\nPlease enter a number between 1 and %d or -1 to exit\n",lim);
scanf("%d",&j);
if(j>0&&j<=lim)
printf("\n%d", arr[j]);
else if(j==-1)
printf("\ngoodbye\n");
else
printf("\nWhoops, that number won't work\n");
}while(j!=-1); }
  else
printf("\nOh Snap, I couldn't open the file.\n");

  fclose(fpIn);

}

Code:

#include "my.h"

int getInput (FILE** fpIn, int** a)
{
int i,j;
  fscanf(*fpIn, "%d",&i);
*a= (int*) calloc(i,sizeof(int));
for(j=0;j<i;j++){
fscanf(*fpIn, "%d",&*a[j]);
}
return i;

}

any help will be greatly appreciated.

**Elysia** · 01-23-2010

Perhaps you should start by fixing your indentation...

**Salem** · 01-23-2010

Re-indented (one-time)

Code:

#include "my.h"

int main(int argc, char* argv[]){
  FILE *fpIn;
  int *arr;
  int lim=0;
  int j=0;

  if(openFiles(&fpIn,argv)){
    lim=getInput (&fpIn, &arr);
    oddEvenSort(arr,lim);
    do{
      printf("\nPlease enter a number between 1 and %d or -1 to exit\n",lim);
      scanf("%d",&j);
      if(j>0&&j<=lim)
        printf("\n%d", arr[j]);
      else if(j==-1)
        printf("\ngoodbye\n");
      else
        printf("\nWhoops, that number won't work\n");
    }while(j!=-1); 
  }
  else
    printf("\nOh Snap, I couldn't open the file.\n");

  fclose(fpIn);

}


#include "my.h"

int getInput (FILE** fpIn, int** a)
{
  int i,j;
  fscanf(*fpIn, "%d",&i);
  *a= (int*) calloc(i,sizeof(int));
  for(j=0;j<i;j++){
    fscanf(*fpIn, "%d",&(*a)[j]);
  }
  return i;

}

You might want to read our FAQ on casting malloc.

Also, don't treat { } as optional.
The cost of adding them (zero if you have a smart IDE) is minimal compared to the time it takes to find some bugs caused by their absence.

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