Error in C program in Dynamic memory allocation

Question

I am using gcc compiler in ubuntu18.10 os. And I don't know why this program is giving Error and Can't even understand the error. The Program is as follows and I presented ERRORS also.

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

float Average(int*, int);

int main()
{
 int *arr;
 int n;
 scanf("%d",&n);
 float sum;
 arr = (int *)malloc(n * sizeof(int));
 for(int i=0;i<n;i++)
    scanf("%d",&arr[i]);

 sum = Average(int *arr, int n);
 printf("%f\n",sum);
 return 0;
}
float Average(int *arr, int size)
{
  int sum;
  int n = size;
  printf("arr: %p\n",&arr);
  printf("size: %p\n",&size);
  printf("sum: %p\n",&sum);

  for(int i=0;i<n;i++)
  {
    sum += arr[i];
  }
  return (sum * 1.0f) / size;
}

Errors are:

Test.c: In function ‘main’:
Test.c:16:16: error: expected expression before ‘int’
  sum = Average(int *arr, int n);
                ^~~
Test.c:16:8: error: too few arguments to function ‘Average’
  sum = Average(int *arr, int n);
        ^~~~~~~
Test.c:4:7: note: declared here
 float Average(int*, int);
       ^~~~~~~

Please Help me to find out why and any reference materials to understand the concept clearly. Thank you

When compiling, always enable the warnings, then fix those warnings. ( for gcc, at a minimum use: -Wall -Wextra -Wconversion -pedantic -std=gnu11 ) Note other compilers use different options to output the same things. Note: the posted code causes the compiler to output 6 warning and 2 error messages. — user3629249
– user3629249, Commented Nov 27, 2019 at 6:50

paxdiablo · Accepted Answer · 2019-11-25 02:59:59Z

2

sum = Average(int *arr, int n);

Type specifiers are something you give in the declaration and definition of the function, not in calls to it. You want:

sum = Average(arr, n);

Some other things you may want to check.

First, the int sum; in Average() does not initialise the value to zero, it sets it to some arbitrary value. That's not going to end well when you just add the integers to it. It should instead be:

  int sum = 0;

Second, unless you're using massive arrays of floating point numbers, it's almost always better to use double for its greater range and precision.

Taking those into account, I probably would have written the function:

double Average(int *arr, int size) {
    double sum = 0;
    for (int i = 0; i < size; ++i)
        sum += arr[i];
    return sum / size;
}

edited Nov 25, 2019 at 2:59

answered Nov 25, 2019 at 2:52

paxdiablo

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1 Comment

EAGALA BHANU PRAKASH Over a year ago

Thank you so much. So, failed to call the function properly.

dbush · Accepted Answer · 2019-11-25 02:52:10Z

0

When you call a function you don't specify the types of the arguments. That's a syntax error. If you look at where you call printf, you'll see that you don't specify the parameter types there. The same goes for your own functions.

So change this:

sum = Average(int *arr, int n);

To this:

sum = Average(arr, n);

answered Nov 25, 2019 at 2:52

dbush

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