How and when are named conditions useful?

What are endless loops ? Why do such loops occur?

Rewrite the following code fragment that saves on the number of comparisons:

if (a == 0) : 
  print ("Zero")
if (a == 1) : 
  print ("One")
if (a == 2) : 
  print ("Two")
if (a == 3) : 
  print ("Three")

Under what conditions will this code fragment print "water"?

if temp < 32 :    
   print ("ice")  
elif temp < 212:  
   print ("water")
else :            
   print ("steam")