2 BytesC++ course_2014_c3_ function basics¶meters and overloading
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The document discusses functions in C++. It explains that functions can be defined in two ways: with declaration/calling/definition or with just declaration and definition. It provides examples of declaring a function that calculates the average of two numbers, calling that function, and defining the function. It also discusses local and global variables and their scopes. Finally, it lists some common predefined functions in C++ like sqrt, pow, abs, and rand.
2 BytesC++ course_2014_c3_ function basics¶meters and overloading
- 1. Kinan keshkeh IT Engineering-Damascus University 3rd year Summer course- 2014 2 bytes team
- 2. • Welcome again ! • Who has any Ques? • So Let’s Go ! • What we will take : • Functions. • parameters& overloading
- 4. Functions •Two ways to write functions in your program: •Declaration / calling / definition
- 5. Functions •Two ways to write functions in your program: •Declaration / calling / definition Before main Inside main After main
- 6. Functions •Two ways to write functions in your program: •Declaration / calling / definition •Declaration + definition / calling
- 7. Functions •Declaration / calling / definition #include<iostream> using namespace std ; Float avg(float x, float y ) ; int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avg : "<<c<<endl; system("pause"); return 0; } float avg(float x, float y ) { return (x+y)/2; }
- 8. #include<iostream> using namespace std ; Float avg(float x, float y ) ; int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avg : "<<c<<endl; system("pause"); return 0; } float avg(float x, float y ) { return (x+y)/2; } Functions •Declaration / calling / definition Declaration
- 9. #include<iostream> using namespace std ; Float avg(float x, float y ) ; int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avg : "<<c<<endl; system("pause"); return 0; } float avg(float x, float y ) { return (x+y)/2; } Functions •Declaration / calling / definition Declaration calling
- 10. #include<iostream> using namespace std ; Float avg(float x, float y ) ; int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avg : "<<c<<endl; system("pause"); return 0; } float avg(float x, float y ) { return (x+y)/2; } Functions •Declaration / calling / definition Declaration calling Definition
- 11. Functions •Declaration + definition / calling #include<iostream> using namespace std ; float avg(float x, float y ) { return (x+y)/2; } int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avssg : "<<c<<endl; system("pause"); return 0; }
- 12. Functions •Declaration + definition / calling #include<iostream> using namespace std ; float avg(float x, float y ) { return (x+y)/2; } int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avssg : "<<c<<endl; system("pause"); return 0; } Declaration+ definition
- 13. Functions •Declaration + definition / calling #include<iostream> using namespace std ; float avg(float x, float y ) { return (x+y)/2; } int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avssg : "<<c<<endl; system("pause"); return 0; } Declaration+ definition calling
- 14. Functions #include<iostream> using namespace std ; float avg(float x , float y ) { return (x+y)/2; } int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avssg : "<<c<<endl; system("pause"); return 0; } Returned value
- 15. Functions #include<iostream> using namespace std ; float avg(float x , float y ) { return (x+y)/2; } int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avssg : "<<c<<endl; system("pause"); return 0; } It could be Void , then no return and no “ = ”
- 16. Functions #include<iostream> using namespace std ; float avg(float x , float y ) { return (x+y)/2; } int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avssg : "<<c<<endl; system("pause"); return 0; } Attention !! “ , ” Not “ ; ”
- 17. Functions #include<iostream> using namespace std ; float avg(float x , float y ) { return (x+y)/2; } int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avssg : "<<c<<endl; system("pause"); return 0; } Variables like in procedures & functions in Pascal !
- 18. Functions #include<iostream> using namespace std ; float avg(float x , float y ) { return (x+y)/2; } int main () { float x,y; cout<<" Enter the first number: n"; cin>>x; cout<<" Enter the second number: n"; cin>>y; float c=avg(x,y); cout<<"the avssg : "<<c<<endl; system("pause"); return 0; } Also , it could be null Float avg()
- 20. Predefined Functions •It’s existing in libraries in C++ •You can call it without writing any definition or declaration !! •You have to put using namespace std with all functions !
- 21. Predefined Functions Name Description Type of Arguments Type of Value Example Value Library Header sqrt Square root double double sqrt(4.0) 2.0 cmath pow Powers double double pow(2.0,3.0) 8.0 cmath abs Absolute value for int int int abs(-7) abs(7) 7 7 cstdlib labs Absolute value for long long long labs(-70000) labs(70000) 70000 70000 cstdlib fabs Absolute value for double double double fabs(-7.5) fabs(7.5) 7.5 7.5 cmath ceil Ceiling (round up) double double ceil(3.2) ceil(3.9) 4.0 4.0 cmath floor Floor (round down) double double floor(3.2) floor(3.9) 3.0 3.0 cmath exit End program int void exit(1); None cstdlib rand Random number None int rand( ) Varies cstdlib srand Set seed for rand unsigned int void srand(42); None cstdlib
- 22. Predefined Functions Name Description Type of Arguments Type of Value Example Value Library Header sqrt Square root double double sqrt(4.0) 2.0 cmath pow Powers double double pow(2.0,3.0) 8.0 cmath abs Absolute value for int int int abs (-7) abs(7) 7 7 cstdlib labs Absolute value for long long long labs(-70000) labs(70000) 70000 70000 cstdlib fabs Absolute value for double double double fabs(-7.5) fabs(7.5) 7.5 7.5 cmath ceil Ceiling (round up) double double ceil(3.2) ceil(3.9) 4.0 4.0 cmath floor Floor (round down) double double floor(3.2) floor(3.9) 3.0 3.0 cmath exit End program int void exit(1); None cstdlib rand Random number None int rand( ) Varies cstdlib srand Set seed for rand unsigned int void srand (42); None cstdlib
- 23. ///Computes the size of a doghouse that can be purchased //given the user’s budget. #include <iostream> #include <cmath> using namespace std; int main( ){ const double COST_PER_SQ_FT = 10.50; //cost per square feet double budget, area, lengthSide; cout << "Enter the amount budgeted for your doghouse $"; cin >> budget; area = budget/COST_PER_SQ_FT; lengthSide = sqrt(area); cout.setf(ios::fixed); cout.setf(ios::showpoint); cout.precision(2); cout << "For a price of $" << budget << endl << "I can build you a luxurious square doghousen" << "that is " << lengthSide << " feet on each side.n"; return 0; } Predefined Functions
- 24. #include <iostream> #include <cstdlib> using namespace std; int main( ){ int month, day; cout << "Welcome to your friendly weather program.n" << "Enter today’s date as two integers for the month and the day:n"; cin >> month; cin >> day; srand(month*day); //using seed number=month*day int prediction; char ans; cout << "Weather for today:n"; do{ prediction = rand( ) % 3 ;// Scaling switch (prediction){ case 0: cout << "The day will be sunny!!n"; break; case 1: cout << "The day will be cloudy.n"; break; case 2: cout << "The day will be stormy!n"; break; default: cout << "Weather program is not functioning properly.n"; } cout << "Want the weather for the next day?(y/n): "; cin >> ans; } while (ans == 'y' || ans == 'Y'); cout << "That's it from your 24-hour weather program.n"; Return 0 ; } Code discussion 3
- 25. Pseudorandom Number Generator Code discussion 3 The code does …
- 26. Local & global Variables !
- 27. Local & global Variables •Local Variables •It’s scope is the current ‘Block’ and all the ‘nested- blocks’ . •You can use the same name of variables in different scopes ! #include<iostream> using namespace std ; int main (){ float x; cout<<" Enter the number: n"; cin>>x; { float x=22; } cout<<"the number x : "<<x<<endl; system("pause"); return 0; } Block!
- 28. Local & global Variables •Local Variables •It’s scope is the current ‘Block’ and all the ‘nested- blocks’ . •You can use the same name of variables in different scopes ! #include<iostream> using namespace std ; int main (){ float x; cout<<" Enter the number: n"; cin>>x; { float x=22; } cout<<"the number x : "<<x<<endl; system("pause"); return 0; }
- 29. Local & global Variables •Local Variables •It’s scope is the current ‘Block’ and all the ‘nested- blocks’ . •You can use the same name of variables in different scopes ! #include<iostream> using namespace std ; int main (){ float x; cout<<" Enter the number: n"; cin>>x; { float x=22; } cout<<"the number x : "<<x<<endl; system("pause"); return 0; }
- 30. Local & global Variables •Local Variables •It’s scope is the current ‘Block’ and all the ‘nested- blocks’ . •You can use the same name of variables in different scopes ! #include<iostream> using namespace std ; int main (){ float x; cout<<" Enter the number: n"; cin>>x; { float x=22; } cout<<"the number x : "<<x<<endl; system("pause"); return 0; }
- 31. Local & global Variables •Local Variables •It’s scope is the current ‘Block’ and all the ‘nested- blocks’ . •You can use the same name of variables in different scopes ! #include<iostream> using namespace std ; int main (){ float x; cout<<" Enter the number: n"; cin>>x; { float x=22; } cout<<"the number x : "<<x<<endl; system("pause"); return 0; }
- 32. Local & global Variables •Local Variables •It’s scope is the current ‘Block’ and all the ‘nested- blocks’ . •You can use the same name of variables in different scopes ! #include<iostream> using namespace std ; int main (){ float x; cout<<" Enter the number: n"; cin>>x; { float x=22; } cout<<"the number x : "<<x<<endl; system("pause"); return 0; }
- 33. •Local Variables
- 34. Local & global Variables •Global Variables •At the first of program ( after “using namespace std” ) •It’s scope , all ‘blocks’ •If you have global variable (name x ) and other local variable ( name x too ) •If you want global x , you will write ::x
- 37. Calling by value & by reference
- 38. Calling by value & by reference
- 39. Calling by value & by reference Without var With var
- 40. Calling by value & by reference Without var With var But “ & ” instead of var .
- 42. •Calling by value •The Output :
- 45. •Calling by reference •The Output :
- 46. Overloading !
- 47. Overloading •The same functions names ,but different meanings •Returned_value Fname ( int v1 , double v1 …. ) •Returned_value Fname ( double v1 , double v1 …. ) •Returned_value Fname ( char v1 , double v1 …. )
- 48. Overloading •The same functions names ,but different meanings •Returned_value Fname ( int v1 , double v1 …. ) •Returned_value Fname ( double v1 , double v1 …. ) •Returned_value Fname ( char v1 , double v1 …. ) Difference here At parameters !
- 49. Overloading •The same functions names ,but different meanings •Returned_value Fname ( int v1 , double v1 …. ) •Returned_value Fname ( double v1 , double v1 …. ) •Returned_value Fname ( char v1 , double v1 …. ) Difference here At parameters ! In numbers of them , and in their kinds
- 50. Overloading •The same functions names ,but different meanings •Returned_value Fname ( int v1 , double v1 …. ) •Returned_value Fname ( double v1 , double v1 …. ) •Returned_value Fname ( char v1 , double v1 …. ) Difference here At parameters ! In numbers of them , and in their kinds Not here at returned value !
- 51. Overloading •The same functions names ,but different meanings •Returned_value Fname ( int v1 , double v1 …. ) •Returned_value Fname ( double v1 , double v1 …. ) •Returned_value Fname ( char v1 , double v1 …. ) •You will see it on operators + , - , * ….
- 53. Overloading
- 54. Overloading
- 55. Overloading
- 57. Homework •Write a program that calls a function , in function the user input a Float number (ex: 3.6) , then the output is “ (3) and (0.6) “ •Write a program that calls a Recursive function , in function the user input an integer number (ex: 3) , then the output is “ (3! = 6) “
- 58. That’s for today That’s for today guys !!
- 59. That’s for today Go and Play !
- 60. 2 bytes team Group : group link Mobile phone- Kinan : 0994385748 Facebook account : kinan’s account 2 bytes team