Tutorial 9 String and Structure
NUS SCHOOL OF COMPUTING
CS1010E PROGRAMMING METHODOLOGY
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Quick Summary
1. Structure introduces the concept of an Object. The Object can
contain many attributes. (Person: Gender, Age, etc.)
1. Two ways to declare a structure:
typedef struct{…}[identifier];
struct [identifier]{…};
2. To retrieve the attributes of a structure use “.” operator:
Person.Gender = “male”;
Person.Age = 20;
3. For Structures with pointers:
Person->Gender = “male”;
Person->Age = 20;
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Q1: Self Implementation of <string.h>
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Q1: Self Implementation of <string.h>
R
A
D
A
Left
R
\0
Right
strlen = right – left;
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Q1: Self Implementation of <string.h>
R
A
D
A
R
\0
s
2
s
1
t
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Q1: Self Implementation of <string.h>
R
A
s
2
s
1
t
R
D
A
R
\0
my_strcpy(s1,s2);
A
\0
R
A
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A
R
\0
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Q1: Self Implementation of <string.h>
R
A
D
A
R
\0
Loop until (s1 becomes \0) or (a difference is found):
s
2
s
1
R
Return the difference
A
D
A
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\0
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Q2: Christmas Carol
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Q2: Christmas Carol
On any particular day:
Constant strings:
“On the ”
“day of Christmas,\n”
“my true…\n”
“and ”
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Q2: Christmas Carol
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Q2: Christmas Carol
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Q2: Christmas Carol
Because a word ends with either of the following:
Space, Comma, Fullstop.
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Q2: Christmas Carol
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Q3: Overlapping Rectangles
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Q3: Overlapping Rectangles
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Q3: Overlapping Rectangles
If the points do not fulfil the pre-condition required,
we just need to swap the two points.
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Q3: Overlapping Rectangles
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Q3: Overlapping Rectangles
It is easier to check if the two rectangles do not overlap:
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Q3: Overlapping Rectangles
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Q4: Snapback Problem
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Q4: Snapback Problem
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Q4: Snapback Problem
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Q4: Snapback Problem
Bubble sort algorithm is used.
This is an improved version of the
bubble sort.
What is the difference?
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Q4: Snapback Problem
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Q4: Snapback Problem
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Q4: Snapback Problem
1
0
0
1
1
…
1
1
0
In the binary sequence, 1 means take the item number j, 0 means omit
the item number j.
We use this binary sequence approach to enumerate all the possible
ways to take the items available and compare the value.
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