/* A comment
*/

// A comment

double average(int count, ...)
{
 //
}

#include 
#include 
int main(void)
{
  int *poin = malloc(4);
  free(poin);
}

https://gcc.gnu.org/onlinedocs/cpp/Macro-Arguments.html

int c = 10;

//  If a header file is included within <>, the preprocessor will search a predetermined directory path to locate the header file. If the header file is enclosed in "", the preprocessor will look for the header file in the same directory as the source file.
#include 
#include "stdio.h"

double da = 3.3;
double db = 3.3;
double dc = 3.4;
int result = (int)da + (int)db + (int)dc; //result == 9

#include 
#define height 10
#ifdef
#endif
#if
#else
#ifndef
#undef
#pragma

// C/C++ program to check if a number is 
// even or not using goto statement 
#include  
using namespace std; 
  
// function to check even or not 
void checkEvenOrNot(int num) 
{ 
    if (num % 2 == 0) 
        goto even; // jump to even 
    else
        goto odd; // jump to odd 
  
even: 
    cout << num << " is evenn"; 
    return; // return if even 
odd: 
    cout << num << " is oddn"; 
} 
  
// Driver program to test above function 
int main() 
{ 
    int num = 26; 
    checkEvenOrNot(num); 
    return 0; 
}

struct account {
  int account_number;
  char *first_name;
  char *last_name;
  float balance;
};

/* hello world */
// hi

// Declare an external function
extern double bar(double x);

// Define a public function
double foo(int count)
{
    double  sum = 0.0;

    // Sum all the values bar(1) to bar(count)
    for (int i = 1;  i <= count;  i++)
        sum += bar((double) i);
    return sum;
}
// Symbol Table:
// Symbol name|Type|Scope
// bar|function, double|extern
// x|double|function parameter
// foo|function, double|global
// count|int|function parameter
// sum|double|block local
// i|int|for-loop statement

int i = 4; /* bit pattern equivalent is binary 100 */
int j = i << 2; /* makes it binary 10000, which multiplies the original number by 4 i.e. 16 */

#include 
int i, a[10];
for (i = 0; i < 10; ++i)
  {
  assert(0 <= i && i < 10);
  a[i] = 10-i;
  }
for (i = 0; i < 10; ++i)
  {
  assert(0 <= i && i < 10);
  assert(0 <= a[i] && a[i] < 10);
  a[a[i]] = a[i];
  }

"hello world"

int *ptr;