Flash Cards

1
Flash Cards

• Project 2 Wed, Oct 2, 2002

2
Specific Problems

• How to control the number of problems.
• How to select the type of problem.
• How to create the numbers in the problem.
• How to compute the users score.
• How to evaluate his performance.

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How to Control the Number of Problems

• The user enters the number of problems that he
  wants.
• Use a for loop to control the presentation of
  problems.

Prompt user for number of problems cin gtgt
numOfProblems for (int i 0 i lt numOfProblems
i) Present the next problem
4
How to Select the Type of Problem

• Let i be the for loop control variable.
• Let the value of i, mod 4, represent the type of
  problem (0 , 1 -, 2 , 3 /).
• Use a switch statement, based on i 4, to select
  the problem type.

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How to Select the Type of Problem

• Define symbolic constants for the cases of the
  switch statement.

const int ADDITION 0 const int SUBTRACTION
1 const int MULTIPLICATION 2 const int
DIVISION 3
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How to Select the Type of Problem
switch (i 4) case ADDITION
Present an addition problem case
SUBTRACTION Present a subtraction
problem
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How to Create the Numbers in the Problem

• For addition and multiplication, use the
  expression
• 1 rand() 10
• to generate each number in the problem.
• For subtraction and division
• Use the above formula to select the second
  operand and the answer.
• Compute back to get the first operand.

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How to Create the Numbers in the Problem

• For example, suppose the problem is subtraction.
• Generate two random numbers, say 6 and 9.
• Let 6 be the second operand and 9 be the answer.
• Compute the first operand 6 9 15.
• Present the user with the problem
• 15 6 ?

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How to Compute the Users Score

• Read the users guess.
• Use a two-way if statement to compare it to the
  correct answer.
• In the True-action, increment a counter that
  counts the number of correct answers.
• After the for loop is finished, use the number of
  correct answers to compute the users score.

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How to Compute the Users Score
if (guess answer) Print a message
Count the correct answer else Print a
message
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How to Evaluate His Performance

• A switch statement is inappropriate since there
  are too many possible values to check.
• Use a multi-way if statement.
• Each case should test a range of values.
• The True-actions should print the appropriate
  messages.