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Hi,
We have default parameters in C++ like at the time of function definition we can give some default value to a parameter. Is there anyhting similar in C#. Because when I gave like in the
below line it was giving me error in the C#, can I use this thing in the C#
public static void sample(int i=100, string s=string.Empty, bool b=true)
{
}
Thanks & Regards,
Md. Abdul Aleem
NIIT technologies
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Default parameters have been added in .NET4 (I'm pretty sure) otherwise you'll have to supply the default in the calling method.
Regards,
Rob Philpott.
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yep.
4.0 is what you want (and that may mean Visual Studio 2010!).
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Ok. Thanks guys I am still using VS 2008 so it wont work for me.
Thanks & Regards,
Md. Abdul Aleem
NIIT technologies
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You need to use .Net 4.0.
The funniest thing about this particular signature is that by the time you realise it doesn't say anything it's too late to stop reading it.
My latest tip/trick
Visit the Hindi forum here.
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LOL, please say it again, just one more time
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Done, but I've now run out of attributes -- how do you do blinking?
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Of-course C# 4.0 , navigate the given link to get better clarification over optional parameter.
Click Me[^]
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You can accomplish a similar effect by defining several versions of the same function, each with a different signature:
public static void sample(int i, string a)
{
bool b= true;
}
public static void sample(int i, bool b)
{
string s = string.Empty;
}
public static void sample(string a, bool b)
{
int i = 100;
}
etc...
If I remember my reading correctly, at run time the calling statement will be matched to the version with matching parameters, and the function will fill in the missing values with the predefined defaults.
Of course, I may be a complete idiot - I'm fairly new to C#. But it's what I would try if I really needed to do this.
Will Rogers never met me.
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I usually implement that pattern as follows in C# 3.5:
public static void sample(int i, string a)
{
_sample(i,false,true,a);
}
public static void sample(int i, bool b)
_sample(i,false,b,string.Empty);
}
public static void sample(string a, bool b)
{
_sample(100,false,b,a);
}
private static void _sample(int i,bool a,bool b,string a_string)
{
}
Software Zen: delete this;
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This is what I use, however I'll admit I feel it slopifies the code base....
I'd blame it on the Brain farts.. But let's be honest, it really is more like a Methane factory between my ears some days then it is anything else...
-----
"The conversations he was having with himself were becoming ominous."-.. On the radio...
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You can use optional parameter .
you can this by this way
class Program
{
static void Main(string[] args)
{
Console.WriteLine(Sum(1, 2, 3).ToString());
Console.WriteLine(Sum( 2, 3).ToString());
Console.ReadLine();
}
static int Sum(params int[] li)
{
int sum=0;
for ( int i = 0 ; i < li.Length ; i++ )
{
sum+=li[i];
}
return sum;
}
}
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You've provided a way which can be only applicable to Integer, Try to expand it for all type of object passed in method.
Like instead of receiving data only in a array of int[], Receive it in object[]. and further check of every item in array whether it's bool,string,object of custom class,float,decimal.
That would be quite cumbersome, optional parameter is the good way , I guess.
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Not exactly elegant but...
public static void sample(int i, string s, bool b)
{
if (i == default(int)) { i = 100; }
if (s == default(string)) { s = string.Empty; }
if (b == default(bool)) { b = true; }
}
Works in .NET Framework 3.5.
Kevin Rucker, Application Programmer
QSS Group, Inc.
United States Coast Guard OSC
Kevin.D.Rucker@uscg.mil
"Programming is an art form that fights back." -- Chad Hower
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Yes, it just returns the framework's default value for the type specified.
Kevin Rucker, Application Programmer
QSS Group, Inc.
United States Coast Guard OSC
Kevin.D.Rucker@uscg.mil
"Programming is an art form that fights back." -- Chad Hower
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So, then, how would I specify 0, null, and false (?) when I want to?
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See the answer I posted to StephenPhillips.
Kevin Rucker, Application Programmer
QSS Group, Inc.
United States Coast Guard OSC
Kevin.D.Rucker@uscg.mil
"Programming is an art form that fights back." -- Chad Hower
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Hmm, surely that misses the advantage of giving optional parameters, i.e. you can call the function without specifying all the input - using this form means you still need to give three values, or it doesn't match the function. Also, in this example, it's impossible to supply 'false' for the third value; false is the default value for a bool, so it would always become true.
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You're absolutely correct, the only way to truly emulate optional parameters like in VB would be to use overloads of the method like this:
public static void sample(int i, string s, bool b)
{
}
public static void sample(int i)
{
sample(i, string.Empty, true);
}
public static void sample(int i, string s)
{
sample(i, s, true);
}
public static void sample(int i, bool b)
{
sample(i, string.Empty, b);
}
public static void sample(string s)
{
sample(100, s, true);
}
public static void sample(string s, bool b)
{
sample(100, s, b);
}
public static void sample (bool b)
{
sample(100, string.Empty, b);
}
public static void sample()
{
sample(100, string.Empty, true);
}
Which swiftly becomes unweildy once you get past three parameters.
Kevin Rucker, Application Programmer
QSS Group, Inc.
United States Coast Guard OSC
Kevin.D.Rucker@uscg.mil
"Programming is an art form that fights back." -- Chad Hower
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visual studio 2010
First and the Foremost: FIGHT TO WIN
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VB .NET has had optional parameters for some time
Looks like it took C# a while to catch up
(Yeah - I know! I shouldn't throw rocks at hornet's nests,
but sometimes you just can't resist!)
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That's possible in C# 4, and the same syntax applies.
-jeff
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