Develop an “or-guard”. In the example above we showed the “and-guard” pattern:

average = count != 0 and float(sum)/count

Develop a similar technique using or .

Compare this with the if-else operator.

Come Out Win. Assume d1 and d2 have the numbers on two dice. Assume this is the come out roll in Craps. Write the expression for winning (7 or 11). Write the expression for losing (2, 3 or 12). Write the expression for a point (4, 5, 6, 8, 9 or 10).

Field Win. Assume d1 and d2 have the numbers on 2 dice. The field pays on 2, 3, 4, 9, 10, 11 or 12. Actually there are two conditions: 2 and 12 pay at one set of odds (2:1) and the other 5 numbers pay at even money. Write two two conditions under which the field pays.

Hardways. Assume d1 and d2 have the numbers on 2 dice. A hardways proposition is 4, 6, 8, or 10 with both dice having the same value. It's the hard way to get the number. A hard 4, for instance is d1+d2 == 4 and d1 == d2. An easy 4 is d1+d2 == 4 and d1 != d2.

You win a hardways bet if you get the number the hard way. You lose if you get the number the easy way or you get a seven. Write the winning and losing condition for one of the four hard ways bets.

Sort Three Numbers. This is an exercise in constructing if-statements. Using only simple variables and if statements, you should be able to get this to work; a loop is not needed.

Given 3 numbers ( X , Y , Z ), assign variables x, y, z so that x ≤ y ≤ z and x, y, and z are from X , Y , and Z . Use only a series of if-statements and assignment statements.

Hint. You must define the conditions under which you choose between x← X , x← Y or x← Z . You will do a similar analysis for assigning values to y and z. Note that your analysis for setting y will depend on the value set for x; similarly, your analysis for setting z will depend on values set for x and y.

Come Out Roll. Accept d1 and d2 as input. First, check to see that they are in the proper range for dice. If not, print a message.

Otherwise, determine the outcome if this is the come out roll. If the sum is 7 or 11, print winner. If the sum is 2, 3 or 12, print loser. Otherwise print the point.

Field Roll. Accept d1 and d2 as input. First, check to see that they are in the proper range for dice. If not, print a message.

Otherwise, check for any field bet pay out. A roll of 2 or 12 pays 2:1, print "pays 2"; 3, 4, 9, 10 and 11 pays 1:1, print "pays even"; everything else loses, print "loses"

Harways Roll. Accept d1 and d2 as input. First, check to see that they are in the proper range for dice. If not, print a message.

Otherwise, check for a hard ways bet pay out. Hard 4 and 10 pays 7:1; Hard 6 and 8 pay 9:1, easy 4, 6, 8 or 10, or any 7 loses. Everything else, the bet still stands.

Partial Evaluation. This partial evaluation of the and and or operators appears to violate the evaluate-apply principle espoused in The Evaluate-Apply Cycle. Instead of evaluating all parameters, these operators seem to evaluate only the left-hand parameter before they are applied. Is this special case a problem? Can these operators be removed from the language, and replaced with the simple if -statement? What are the consequences of removing the short-circuit logic operators?