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

#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. 

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

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;
}

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

Which of these statements is/are true?

What is the output of the following program that compiles correctly? (Hint: When evaluating logical operators, the compiler ignores the remainder of the expression when it is sure of the final answer at any point of evaluation of the sub-expression - something often referred to as "short-circuit evaluation". This is a cryptic hint, I know, but enjoy unravelling it and discovering its meaning and implication!)

#include <stdio.h>

int main()
{
  int a= -2, b= -1, c = 0, d = 1, e = 2;
  int r1, r2;
  r2 = a++ || ++b || c++ || ++d || e;   
  r1 = a && b++ && ++c && d++ && ++e;  
  printf("%d %d %d\n", r1,r2,a+b+c+d+e);
  return 0;
}