Tuesday, December 26, 2006

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Tuesday, December 26, 2006

• There was a most ingenious architect who
  contrived a new method for building houses,
• By beginning at the roof and working downward to
  the foundation.
• - Jonathan Swift, Gullivers Travels

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Equivalent statements?
Nested Switch
char ch1, ch2 cingtgtch1gtgtch2 switch(ch1)
case 'A' cout ltlt "This A is part of outer
switch\n" switch(ch2) case 'A' cout
ltlt "This A is part of inner switch\n" break
case 'B' cout ltlt "This B is part of inner
switch\n" break case 'B' cout ltlt
"This B is part of outer switch\n" break
3
Equivalent statements?
Nested Switch
char ch1, ch2 cingtgtch1gtgtch2 switch(ch1)
case 'A' cout ltlt "This A is part of outer
switch\n" switch(ch2) case 'A' cout
ltlt "This A is part of inner switch\n" break
case 'B' cout ltlt "This B is part of inner
switch\n" break case 'B' cout ltlt
"This B is part of outer switch\n" break
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• Top down design

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Benefits of Top Down Design

• Subtasks, or functions in C, make programs
• Easier to understand
• Easier to change
• Easier to write
• Easier to test
• Easier to debug
• Easier for teams to develop

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• Hardware design
• Subparts or modules
• Interface
• Software design

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• Three places where variables are declared
• Inside functions local variables
• In the definition of function parameters formal
  parameters
• Outside of all functions global variables

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• local variables are created when function is
  called and destroyed when function is exited.
• formal parameters are used like local variables.
  Their value is lost once the function terminates.
  They have a special task of receiving the value
  of arguments.
• global variables hold their value throughout the
  lifetime of your program

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• int sum(int x, int y)
• int main()
• int answer
• coutltltIn main
• answer sum(2,3)
• coutltltanswer
• return 0
• int sum (int x, int y)
• int zxy
• coutltltIn sum
• return z

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• int sum(int x, int y)
• int main()
• int answer, num1, num2
• cingtgtnum1gtgtnum2
• coutltltIn main
• answer sum(num1,num2)
• coutltltanswer
• return 0
• int sum (int x, int y)
• int zxy
• coutltltIn sum
• return z

Function Call
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(No Transcript)
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Examples of Functions
include ltiostream.hgt double pi(void) int
main(void) double answer answerpi() coutltlt"
answer is "ltltanswerltltendl return 0 double
pi(void) double value3.14159 coutltlt"I return
value of pi when called"ltltendl return value
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Examples of Functions
I return value of pi when called answer is
3.14159
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include ltiostream.hgt double area(double
radius) double pi() int main(void) double
answer answerarea(7.5) coutltlt"answer is
"ltltanswerltltendl return 0 double area(double
radius) double valuepi()pi()radius return
value double pi() return 3.14159 //we can
return a constant also
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• Output?
• answer is 74.0219

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include ltiostream.hgt double Add2(double d, char
c, int i) int main(void) double dd4.4 char
cc'b' int ii15 double ansAdd2(dd,cc,ii) c
outltltansltltendl coutltltddltlt"\t"ltltiiltlt"\t"ltltccltltend
l return 0 double Add2(double d, char c,
int i) dd2 ii2 cc2 coutltltdltlt"\t"ltltilt
lt"\t"ltltcltltendl return d
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• Output?

6.4 17 d 6.4 4.4 15 b

• Parameter list order is important!

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• int main()
• int x30, y40, z45, ans1, ans2
• x (y) (x/y) 35z
• x (z98-y)78 53/z
• x / (3467y(zx))
• ans1 3x50y
• x70, y80, z85
• x (y) (x/y) 35z
• x (z98-y)78 53/z
• x / (3467y(zx))
• ans2 3x50y
• coutltltans1ltltendlltltans2

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• int calculate(int a, int b, int c)
• int main()
• int x30, y40, z45, ans1, ans2
• ans1 calculate(x, y, z)
• x70, y80, z85
• ans2 calculate(x, y, z)
• coutltltans1ltltendlltltans2
• int calculate(int a, int b, int c)
• int value
• a (b) (a/b) 35c
• a (c98-b)78 53/c
• a / (3467b(ca))
• value 3a50b
• return value

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• header files
• predefined functions include ltmath.hgt

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Math library
include ltmath.hgt sin(x), cos(x), tan(x),
asin(x), acos(x), atan(x), sinh(x), cosh(x),
tanh(x), exp(x), log(x), log10(x), pow(x,y),
sqrt(x), ceil(x), floor(x)
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int main() int num double sine_val
for(num1 num lt 100 num) sine_val
sin(num3.14/180.0) cout ltlt num ltlt"
"ltltsine_valltlt "\n" return 0
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• include ltstdlib.hgt
• int rand(void)

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• int sum(int x, int y)
• int main()
• int answer, x, y
• cingtgtxgtgty
• coutltltIn main
• answer sum(x,y)
• coutltltanswer
• return 0
• int sum (int x, int y)
• int zxy
• coutltltIn sum
• return z

Function Call