Transcript CS 177

Week 5 - Friday
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What did we talk about last time?
Repetition
while loops
while( condition )
{
statement1;
A whole statement2;
bunch of
statements …
statementn;
}
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Let’s say that you wanted to write a program
to guess a number that a person had come up
with
The number is between 1 and 100
Every time the computer guesses a number,
the person enters:
H
L
F
if the number is too high
if the number is too low
if the number was found
Start with the minimum and maximum of the
range
2. Find the midpoint
3. Ask the user if the midpoint is correct
4. If the answer is too high, go to Step 1 using the
minimum and the midpoint - 1 as the new
range
5. If the answer is too low, go to Step 1 using the
midpoint + 1 and the maximum as the new
range
6. If the midpoint is correct, you’re done!
1.
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Just as with if-statements, it’s possible to
nest loops
A repetitive task can be done inside of
another repetitive task
Be careful! You can make the computer do a
lot of work
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Triangular numbers are 1, 3, 6, 10, …
 1=1
 3=1+2
 6=1+2+3
 10 + 1 + 2 + 3 + 4
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Let’s write a program that expresses the nth
triangular number by printing 1 on the first
line, 1 and 2 on the second line, 1, 2, and 3 on
the third line, and so on
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for loops
More loop examples
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Keep reading Chapter 5
Keep working on Project 2