In C++ if/else if /else statements are used to express a multiple alternative, in which exactly one from a mutually exclusive set of choices is selected to be executed. Nested if statements are used to express a selection from multiple alternatives when there are multiple conditions for each selection.

/* value of integer choice used to select one of four possible values 
for x */
if (choice == 1)  x = n;
else if (choice == 2) x = n * n;
else if (choice == 3) x = n * n * n;
else x = 0;  

/* value of integer choice and value of boolean available
used to select one of four possible values for x */

if (choice == 1)
{  
   if (positive)
      x = n;
   else
      x = -n;
}      
   
else  /* (choice == 2) */
{  
   if (positive)
      x = n * n;
   else
      x = -n * n;
}