String variable as parameter!

[Gigsman]

public void Foo(string one)
{
one = "two";
}


main()
{
string one = "one";
Foo(one);
Console.writeline(one);
}

What is return result? String variable 'one' is "one" or "two"?


thanks!

--Tony

 

[Marc Gravell]

As it stands, "one" will be written to the console.

(warning: slightly confusing terminology ahead; read slowly...)
normally for reference types (such as the string class) the *reference* to
the object is passed *by value*; by *reassigning* (one = "two"), you break
this relationship. Note that if instead you had the below you would see
"two", since we haven't *reassigned* the variable (we have just changed
properties of the referenced item):
class SomeClass {
public string Text;
}
public void Foo(SomeClass one)
{
one.Text = "two";
}
main()
{
SomeClass one = new SomeClass();
one.Text = "one";
Foo(one);
Console.writeline(one.Text);
}
===
equally, if we used "ref string one" as the parameter (and called via
"Foo(ref one)") then our reassignment would be reflected in our calling
code.

Marc

 

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

Dont you think you would have get a faster , 100% correct answer by just
running it?