Concepts:
A simple example on the use of the loop constructs: while, do-while e for

Text:
Realize a program that:

• prints as output the numbers between 0 and n
• only n>0 must be taken into account

Solution (while):

while_1.c

/*
  Realize a program that prints as output numbers between 0 and n (with n>0).
*/
 
#include <stdio.h>
 
int main()
{
  unsigned int i, n;
 
  printf("Number of elements: ");
  scanf("%d", &n);
 
  i=0;
  while(i<=n){
    printf("%3d\n", i);
    i++;
  }
 
  return 0;
}

Solution (do-while):

do-while_1.c

/*
  Realize a program that prints as output numbers between 0 and n (with n>0).
*/
 
#include <stdio.h>
int main()
{
  unsigned int i, n;
 
  printf("Number of elements: ");
  scanf("%d", &n);
 
  i=0;
  do{
    printf("%3d\n", i);
    i++;
  }while(i<=n);
 
  return 0;
}

Soluzione (for):

for_1.c

/*
  Realize a program that prints as output numbers between 0 and n (with n>0).
*/
 
#include <stdio.h>
 
int main()
{
  unsigned int i=0, n;
 
  printf("Number of elements: ");
  scanf("%d", &n);
 
  for(i=0;i<=n;i++){ /* This instruction can be equivalently written as for(;i<=n;i++), but only because the i variable has been initialized before */
    printf("%3d\n", i);
  }
 
  return 0;
}