C# 0 The Complete Reference

n

 is 

returned as 

GetParts( )

’s return value. Second, the fractional portion of 

n

 is passed back to 

the caller through the 

out

 parameter 

frac

. As this example shows, by using 

out

, it is possible 

for one method to return two values.

Of course, you are not limited to only one 

out

 parameter. A method can return as many 

pieces of information as necessary through 

out

 parameters. Here is an example that uses 

two

out

 parameters. The method 

HasComFactor( )

 performs two functions. First, it determines 

if two integers have a common factor (other than 1). It returns 

true

 if they do and 

false

otherwise. Second, if they do have a common factor, 

HasComFactor( )

 returns the least and 

greatest common factors in 

out

 parameters.

// Use two out parameters.

using System;

class Num {

  /* Determine if x and v have a common divisor.

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T h e   C #   L a n g u a g e

     If so, return least and greatest common factors in

     the out parameters. */

  public bool HasComFactor(int x, int y,

                           out int least, out int greatest) {

    int i;

    int max = x < y ? x : y;

    bool first = true;

    least = 1;

    greatest = 1;

    // Find least and greatest common factors.

    for(i=2; i <= max/2 + 1; i++) {

      if( ((y%i)==0) & ((x%i)==0) ) {

        if(first) {

          least = i;

          first = false;

        }

        greatest = i;

      }

    }

    if(least != 1) return true;

    else return false;

  }

}

class DemoOut {

  static void Main() {

    Num ob = new Num();

    int lcf, gcf;

    if(ob.HasComFactor(231, 105, out lcf, out gcf)) {

      Console.WriteLine("Lcf of 231 and 105 is " + lcf);

      Console.WriteLine("Gcf of 231 and 105 is " + gcf);

    }

    else

      Console.WriteLine("No common factor for 35 and 49.");

    if(ob.HasComFactor(35, 51, out lcf, out gcf)) {

      Console.WriteLine("Lcf of 35 and 51 " + lcf);

      Console.WriteLine("Gcf of 35 and 51 is " + gcf);

    }

    else

      Console.WriteLine("No common factor for 35 and 51.");

  }

}

In

Main( )

, notice that 

lcf

 and 

gcf

 are not assigned values prior to the call to 

HasComFactor( )

. This would be an error if the parameters had been 

ref

 rather than 

out

. The method returns either 

true

 or 

false

, depending upon whether the two integers 

have a common factor. If they do, the least and greatest common factors are returned 

in the 

out

 parameters. The output from this program is shown here:

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