14, function output parameters, recursion

1, the function input parameter is directly available to the function, which is equivalent to a variable that has already been assigned. The output parameter is equivalent to defining a variable, assigning it in a function, and then calling the function to take the assigned value out of the function. Example 1: Enter the value of the a,b,c, judging is not a unary two-time equation:classProgram { Public stringFangcheng (DoubleADoubleBDoubleC out DoubleX1, out Doublex2) {            DoubleD = b * B-4AC; if(A = =0) {x1=-b/C; X2=-b/C; return "not a unary two-time equation ."; }            Else             {                     if(D <0) {x1= -1; X2= -1; return "No solution"; }                Else if(d = =0) {x1=-(b + math.sqrt (d))/(2*a); X2=-(B-math.sqrt (d))/(2*a); return "There are two equal real number roots."; }                Else{x1=-(b + D)/(2*a); X2=-(b-d)/(2*a); return "There are two unequal real-root"; }            }        }        Static voidMain (string[] args) {Program AAA=NewProgram (); Console.WriteLine ("Please enter the value of a:"); DoubleA =int.            Parse (Console.ReadLine ()); Console.WriteLine ("Please enter a value for B:"); Doubleb =int.            Parse (Console.ReadLine ()); Console.WriteLine ("Please enter a value for C:"); Doublec =int.            Parse (Console.ReadLine ()); Doublex1, x2; Console.WriteLine (Aaa.fangcheng (A,b,c, outX1, outx2)); Console.WriteLine ("x1="+ x1 +"\ n"+"x2="+x2);        Console.ReadLine (); }}2, recursive Example 2: (1The monkey Peaches, the day after picking half of the previous one, and the seventh day there is one, a total of a few? (2A man drove a flock of sheep and sold it to a village 1/3 Plus one, there are 2 in the seventh village, how many in total? (3A pair of young rabbits two months into a rabbit and gave birth to a pair of young rabbits, 9 months after the pair? classProgram { Public intTaozi (intDay ) {            if(Day = =7)            {                return 1; }            Else            {                intn =2* (Taozi (day +1) +1); returnN; }        }         Public intYangintcun) {            if(Cun = =7)            {                return 2; }            Else            {                intn =3* (Yang (cun +1) +1); returnN; }        }         Public intTuziintYue) {            if(Yue = =0)            {                return 1; }            Else            {                intn = Tuzi (yue-2)*2; returnN; }        }        Static voidMain (string[] args) {Program DD=NewProgram (); Console.WriteLine (Dd.taozi (1)); Console.WriteLine (Dd.yang (1)); Console.WriteLine (Dd.tuzi (9));        Console.ReadLine (); }}

14, function output parameters, recursion