Struct, pointers, getting the field value by the pointer

Question

I have something similar to this code in my application:

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

typedef struct STH
{
  double *buff;
  int size;
}STH;

void fun1(STH *s)
{
  fun3(s->buff, s->size);
}

void fun3(double *buff, int n)
{
  int i = 0;
  printf("N = %d\n", n);
  for(i=0; i<n; i++)
     printf("%d\n", buff[i]);
}

void fun2()
{
  STH s;

  s.size = 4;
  s.buff = malloc(sizeof(double) * s.size);

  fun1(&s);
}

int main()
{
    fun2();
    return 0;
}

When I try to print out the buffer in fun3, gdb says that there is an error in fun3. When I try to print out (in fun2) the value of the s->size, there is an error (instead of 4 it prints out strange numbers ....)

"%f\n" , s.buff = calloc(s.size, sizeof(double))

BLUEPIXY
– BLUEPIXY

2014-01-05 18:51:19 +00:00
Commented Jan 5, 2014 at 18:51 — BLUEPIXY
– BLUEPIXY, Commented Jan 5, 2014 at 18:51
fun3(..){..} before fun1(..){..}

BLUEPIXY
– BLUEPIXY

2014-01-05 18:54:28 +00:00
Commented Jan 5, 2014 at 18:54 — BLUEPIXY
– BLUEPIXY, Commented Jan 5, 2014 at 18:54

Marian · Accepted Answer · 2014-01-05 18:54:48Z

1

buff[i] is a floating point number, use %f format specifier to print it. I.e. use:

printf("%f\n", buff[i]);

instead of

printf("%d\n", buff[i]);

Also you have not initialized your array to some values. It will contain (and print) random values.

answered Jan 5, 2014 at 18:54

Marian

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