How do you call repeat/recursive in C#? - Overclock.net

Licht · 12-10-07

I've used other languages and i just used.

Repeat (<number of times>)
{
;
}

But in C# i can't seam to find this function...

dante020 · 12-10-07

for(int i=start; i<end; i++)
{

}

DuckieHo · 12-10-07

That's not recursive... that is just a simple "For Loop"

Recursive is:

Code:

Repeat (Exit Criteria)
{
    Repeart (Exit Criteria);
}

dante020 · 12-10-07

I know its not recursive but I believe that is what he wanted judging from his example.

DuckieHo · 12-10-07

Quote:

Originally Posted by dante020

I know its not recursive but I believe that is what he wanted judging from his example.

Wasn't directed at you... I was referring to the title.

Licht... For, Select/Case, and While looping is pretty standard in all languages.

dante020 · 12-10-07

My bad

Licht · 12-14-07

Quote:

Originally Posted by dante020

for(int i=start; i<end; i++)
{

}

Can you give me a more in depth explanation?

Quote:

That's not recursive... that is just a simple "For Loop"

Recursive is:

That is C# right? Giving me errors, of course i don't fully understand the way to use either (C# noob.)

Polska · 12-16-07

Quote:

Originally Posted by Licht

That is C# right? Giving me errors, of course i don't fully understand the way to use either (C# noob.)

More concrete examples.

1)This for loop will run 6 times. First "i" is initialized to 0, then checked against the condition "i<6", if true runs code "do something" then "i" is incremented by 1, and the loop runs over and over until i<6 fails (so when i is 6). So the code inside the for loop would run 6 times in this case.

Code:

for(int i=0; i<6; i++){
    //do something
}

2) Recursion sample, program will use recursion and print all positive numbers less then or equal to 10. Here when the function lessthenorequal(Number) is called, it prints Number, decrements Number by 1, and calls itself with the new decremented value.

It is important to notice that a call to lessthenorequal(Number) does not exit until the call it makes to itself exits (if it makes a call to itself).

Code:

using System;

class Program {
    static void lessthenorequal(int a) {
        if (a >= 0) {
            Console.Write("{0}, ", a);
            a--;
            lessthenorequal(a);
        }
    }

    static void Main() {
        const int Number = 10;

        Console.WriteLine("Number less then or equal to {0}", Number);
        lessthenorequal(Number);

        Console.WriteLine();
    }
}

Lets trace a call to lessthenorequal(2):

Code:

lessthenorequal(2)
  prints 2,
  decrements 2 by 1
  calls lessthenorequal(1)
    prints 1,
    decrements 1 by 1
    calls lessthenorequal(0)
      prints 0,
      decrements 0 by 1
      calls lessthenorequal(-1)
        does nothing
      lessthenorequal(-1) exits
    lessthenorequal(0) exits
  lessthenorequal(1) exits
lessthenorequal(2) exits

I'm not the best teacher but I hope that explains things a tad for you. Other constructs you may want to google and get familiar with are: "while loop", "Do While Loop", "For Each Loop". They all have their uses at different times, sometimes it is suitable to use several depending on your choice.

Licht · 12-16-07

Quote:

Originally Posted by Polska

More concrete examples.

1)This for loop will run 6 times. First "i" is initialized to 0, then checked against the condition "i<6", if true runs code "do something" then "i" is incremented by 1, and the loop runs over and over until i<6 fails (so when i is 6). So the code inside the for loop would run 6 times in this case.

Code:

for(int i=0; i<6; i++){
    //do something
}

2) Recursion sample, program will use recursion and print all positive numbers less then or equal to 10. Here when the function lessthenorequal(Number) is called, it prints Number, decrements Number by 1, and calls itself with the new decremented value.

It is important to notice that a call to lessthenorequal(Number) does not exit until the call it makes to itself exits (if it makes a call to itself).

Code:

using System;

class Program {
    static void lessthenorequal(int a) {
        if (a >= 0) {
            Console.Write("{0}, ", a);
            a--;
            lessthenorequal(a);
        }
    }

    static void Main() {
        const int Number = 10;

        Console.WriteLine("Number less then or equal to {0}", Number);
        lessthenorequal(Number);

        Console.WriteLine();
    }
}

Lets trace a call to lessthenorequal(2):

Code:

lessthenorequal(2)
  prints 2,
  decrements 2 by 1
  calls lessthenorequal(1)
    prints 1,
    decrements 1 by 1
    calls lessthenorequal(0)
      prints 0,
      decrements 0 by 1
      calls lessthenorequal(-1)
        does nothing
      lessthenorequal(-1) exits
    lessthenorequal(0) exits
  lessthenorequal(1) exits
lessthenorequal(2) exits

I'm not the best teacher but I hope that explains things a tad for you. Other constructs you may want to google and get familiar with are: "while loop", "Do While Loop", "For Each Loop". They all have their uses at different times, sometimes it is suitable to use several depending on your choice.

Code:

for(int i=0; i<6; i++){
    //do something
}

I wanna focus on this, i have a few questions. What exactly is the syntax for this?

Code:

for(first argument; 2nd argument; 3rd argument)

What exactly gos in for each argument? Is it always used to initiate a variable, run a check, then perform a mathematical change to the variable?

Polska · 12-16-07

The general Syntax would be:

syntax:

Code:

for (statement1; expression; statement2)
    statement[s]3

curly brackets used to nest several statements
for (statement1; expression; statement2) {
    statement3;
    statement4;
    statement5;
}

statement2 doesn't necessarily have to correlate to statement1, but generally it does. This way you keep the loop structure seperate from whatever you want to loop.

You could however write

Code:

 for (int i = 0; i < 6; ) {
     Console.WriteLine("hi");
     i++;
 }

or even

Code:

int i = 0;
for (; i < 6; ) {
   Console.WriteLine("hi");
   i++;
}

and they are equivalent to;

Code:

for (int i = 0; i < 6; i++) {
     Console.WriteLine("hi");
}

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How do you call repeat/recursive in C#?

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