Computer Science 1 Honors

Transcription

1 Computer Science 1 Honors

2 Will be

3 Most methods are too complex simply to call them and let them do their job. Methods almost always need more information. For example, a method that finds a square root, needs to know what number to take the square root of.

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8 The method max in the Math class: takes two numbers returns the bigger number max expects two numbers as parameters These are its formal parameters. When you call Math.max(6,8) 6 & 8 are passed to max as its actual parameters.

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11 public mymethod(int static foo, void String mymethod(); par);

12 parameters public mymethod(int static foo, void String mymethod(); par);

13 Two parameters are declared integer name foo String named bar Parameter types mymethod(int foo, String par);

14 Two parameters are declared integer name foo String named par Parameter names mymethod(int foo, String par);

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16 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println();

17 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println();

18 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int i=0; i<length; i++) System.out.print(mark); System.out.println( );

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20 name Recall that up until now we ve left them blank

21 One parameter (in this case, the String foo): myclass.mymethod( Foo ); More than one parameter: Math.max(4,9); Can also be variables or expressions: Math.max(x,y+z);

22 Parameters must be in the same order as specified in the method Recall our drawbar method required an integer and a string OK Bad drawbar(6, = ); drawbar( =,6);

23 You must pass the same number of parameters that the method expects Bad Math.max(4,7,9);

24 Include the types when declaring parameters but never when passing them Don t do this when calling drawbar: drawbar(int myint, String mark);

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26 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); drawbar Method

27 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); Calls the drawbar Method and passes 6 and * as parameters

28 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); In drawbar, length is 6 and mark is *

29 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); Prints 6 stars

30 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); When the method is done, it exits.

31 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); drawbar is called with length 3 and mark =

32 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); Prints 3 equal signs

33 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); The drawbar exits

34 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); Again program continues with next statement after method call

35 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); drawbar is called again with length 6 and mark *

36 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); 6 stars print

37 //Draws a bar made using the String mark of a given length public static void drawbar (int length, String mark){ for(int num=0; num<length; ++num) System.out.print(mark); System.out.println(); //Calling code DrawBar(3, = ); Again program continues with next statement after method call

38 Questions?