There are two places where swapping is done. This could not be substituted with a function that can be invoked twice.

Which of the following function declarations (also called as "function prototypes") are valid?

void func(int x, int y)
{
  int z;
  scanf("%d", &z);
  return z;
}

#include <stdio.h>
int main() 
{
    int i = 0;
    while (i < 5) {
        if (i % 2 == 0)
        {
                putchar('*');
                continue;
        }
        printf("%d ", i);
        i++;
    }
    return 0;
}

Function calls that return void may not be used as a part of an expression. 

How many times does the while loop run?

#include <stdio.h>
int main()
{
  int i = 1;
  while (i <= 5)
    printf("%d ", i++);
  putchar('\n');
  return 0;
}

Which of these statements is/are true?

The principles of top–down design and structured programming dictate that a program should be divided into a main module and its related modules. 

The address operator (&) is used to tell the compiler to store data at an address.