Compiler errors

vital_101 · #1 12-Jan-2006, 10:01

I've been doing some coding in C lately, and I'm having trouble figuring out why it won't compile. I've took care of most of the compiler errors, but for the rest I'm not even sure what they mean. I'm compiling using GCC on a Sun Solaris.
My code:

CPP / C++ / C Code:

#include <stdio.h>
#include <stdlib.h>
#define max 2048

int
main()
{
  int count = 0, n, nextval, d[max];
  void getdata(int d[], char *n);

  getdata(int d[max], char *n);
  printf("The value in place 4 is %d\n", d[3]);
  exit(0);
}
 
void 
getdata(int d[], char *n) 
{
  int count, nextval; 
  while(count < max && (n = scanf("%d", &nextval)) != EOF) {
      d[count++] = nextval;
    }
}

My compiler errors:

Quote:

test.c: IN function 'main':
test.c:11: error: parse error before "int"
test.c: In function 'getdata':
test.c:20: warning: assignment makes pointer from integer without a cast
test.c:20: warning: comparison between pointer and integer

Thanks for any help.
/vital_101

alcoholic · #2 12-Jan-2006, 10:38

See the changed code...it can be bettered in many ways...just made it work for the moment

CPP / C++ / C Code:

#include <stdio.h>
#include <stdlib.h>

#define max 5

void getdata(int d[]);

int main()
{
  int nextval, d[max];
  getdata(d);
  printf("The value in place 4 is %d\n", d[3]);
  exit(0);
}
 
void getdata(int d[]) 
{
  int count=0, nextval; 
  int n;
  while(count < max && (n = scanf("%d", &nextval)) != EOF) {
      d[count] = nextval;
	  count++;
    }
}

netnut · #3 12-Jan-2006, 11:05

Quote:

while(count < max && (n = scanf("%d", &nextval)) != EOF) {

I dunno C, never used it, but I know C++ so think I should be able t help you with one of those errors. The mistake in the above code fragment is that u a have declared n as "int *n", what this does is declare n as a pointer to an integer variable; that is it can store the "memorey addres" of an integer variable and not any int "value".

The correct way would be:

CPP / C++ / C Code:

int *n;
int a=10;
n=&a; //&=>"address of" operator

Here, n stores the address of a (which is in a hexadecimal format I think), n can be called an alias (Senior members tell me if i'm mistaken) of the variable a. And what u end up comparing in the while() loop is an "address" of an integer and an integer value.
Think over it. I'm too sleepy right now, to think anymore.

Logging off....

Saving your settings......

My Mind is shutting down......

[Blup]

Netnut.

WaltP · #4 12-Jan-2006, 13:25

Because when calling a function:

CPP / C++ / C Code:

getdata(int d[max], char *n);

you don't specify the function definition, you specify the function parameters. Change it to:

CPP / C++ / C Code:

getdata(d, &n);

d - passing the address of the array
n - pass the address of the variable

My personal preference for the function is:

CPP / C++ / C Code:

void 
char getdata(int d[]) 
{
   int count, nextval; 
   while(count < max && (n = scanf("%d", &nextval)) != EOF) 
   {
      d[count++] = nextval;
   }
   return (n);
}

I dislike void functions passing back values via the parameter list. They are harder to debug and less flexible.

Also, I question whether your n has a useful value. It returns 1 if there are more than count values entered, and 0 when there are fewer.

davekw7x · #5 12-Jan-2006, 13:53

Quote:

Originally Posted by WaltP

[/c]
I dislike void functions passing back values via the parameter list. They are harder to debug and less flexible.

An excellent point of style for functions that return only one thing.

Quote:

Originally Posted by WaltP

Also, I question whether your n has a useful value.

n is equal to the last value returned by scanf() before control left the loop: It could be 0; it could be 1; it could be EOF. Anyhow, like WaltP, I don't see the usefulness of having the function return the value of n.

Maybe it should return count, since there is no other way for the calling program to know how many items were successfully scanned. (And, of course, that means that count should be initialized to at the beginning of the function.)

Regards,

Dave

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