Passing by Value

1
Passing by Value

• Passing by Value
• Formal Parameters, place holders in the header of
  the function
• Actual Parameters, parameters contained in the
  function call

2
Passing by Value

• void print_nums (int num1, int num2, int num3)
• cout ltlt endl
• cout ltlt Number 1 is ltlt num1 ltlt endl
• cout ltlt Number 2 is ltlt num2 ltlt endl
• cout ltlt Number 3 is ltlt num3 ltlt endl

3
Passing by Value

• int main( )
• number_1 10
• number_2 20
• number_3 30
• cout ltlt The Numbers are ltlt endl
• print_nums ( number_1, number_2, number_3 )
• cout ltlt system(Pause)

4
Passing by Value

• void print_nums ( int num1, int num2, int num3)

Number_1 10 Number_2 20 Number_3
30 print_nums ( number_1, number_2, number_3
) cout ltlt system(Pause)
5
Passing by Value

• The Numbers are
• Number 1 is 10
• Number 2 is 20
• Number 3 is 30

Screen
6
Passing by Reference

• Passing by Reference
• Variable Parameters, place holders in the header
  of the function
• Actual Parameters, parameters contained in the
  function call

7
Passing by Reference

• void print_nums ( int num1, int num2, int
  num3)
• cout ltlt endl
• cout ltlt Number 1 is ltlt num1 ltlt endl
• cout ltlt Number 2 is ltlt num2 ltlt endl
• num3 num1 num2
• cout ltlt Number 3 is ltlt num3 ltlt endl

8
Passing by Reference

• int main( )
• number_1 10
• number_2 20
• number_3 number_1 number_2
• cout ltlt The Numbers are ltlt endl
• cout ltlt number_1 ltlt number_2 ltlt number_3) ltlt
  endl
• print_nums ( number_1, number_2, number_3 )
• cout ltlt Number 3 in main is ltlt number3 ltlt
  endl
• cout ltlt system(Pause)

9
Passing by Reference

• void print_nums ( int num1, int num2, int num3)

number_1 10 number_2 20 number_3
number_1 number_2 print_nums ( number_1,
number_2, number_3 )
address
400
404
408
10
Passing by Reference

• The Numbers are 10 20 30
• Number 1 is 10
• Number 2 is 20
• Number 3 is 200
• Number 3 in main is 200

Screen
11
Modular Program Age

• include ltiostreamgt
• include ltiomanipgt
• include ltstringgt
• using namespace std
• void read_year( int)
• void compute_age (int, int)
• void display_age (int age)
• int main( )
• int birth_year, age
• read_year(birth_year)
• compute_age(age, birth_year)
• display_age(age)
• cout ltlt system(Pause)
• return 0

12
Modular Program Age

• //
  
• void read_year( int birth_year)
• cout ltlt endl
• cout ltlt Enter year of birth ltlt endl
• cin gtgt birth_year
• cout ltlt endl
• //
  
• void compute_age (int age, int birth_year)
• const current_year 2005
• age current_year birth_year

13
Modular Program Age

• //
  
• void display_age (int age)
• cout ltlt endl
• cout ltlt Your age after this years birthday is
  ltlt age ltlt . ltlt endl
• cout ltlt endl