More of Function Parameters

Lets look into detail of two more parameters in C# functions , out and ref. Of course , we have seen the usual stuff here. Perhaps we could take a brief look into it again and talk about the difference between variable scope , which I remember , have been posted before too. Nonetheless , lets start.

int userAge; //variable outside the function getAge()

public int getAge(int userId)
{
   int userAge; //variable local to the function getAge()
   // codes to get the age from id
   return userAge;
}

userAge = getAge(12);

As you can see from my comments , although there are two variables called “userAge” , it doesn’t matter , although as a good programming practice , they should have been given different names. It is because on of them is only within the function while the other is within the class or namespace. And of course , the function returns an integer back to the caller. Suppose you want to return two variables , how do we go about doing that? You can only return one value if you write it as above. It won’t work if you coded return statement twice. But suppose you must return two variables.

Function With “out” Parameters

int userAge; //variable outside the function getAge()
int userEnglishGrade;

public void getInfo(out int userAge , out userEnglishGrade)
{
   userAge = 20;
   userEnglishGrade = 2;
}

getInfo(out userAge , out userEnglishGrade);

Console.WrintLN(userAge); //prints out 20
Console.WrintLN(userEnglishGrade); //prints out 2

As you can see , by using out , I can return the two variables , after assigning them with respective values. Of course , it doesn’t return anything because it is a “void” method. Pls take not that my out variables , userAge and userEnglishGrade were not initialised. They were only declared. Initializing takes place in the function which then returns them to the caller , in this case , the program. We now take a look at the parameter using ref keyword.

Function With “ref” Parameters

int userAge = 10; //variable outside the function getAge()
int userEnglishGrade = 2;

public void getInfo(ref int userAge , ref userEnglishGrade)
{
   userAge = 20;
   userEnglishGrade = 3;
}

Console.WrintLN(userAge); //prints out 10
Console.WrintLN(userEnglishGrade); //prints out 2

getInfo(ref userAge , ref userEnglishGrade);

Console.WrintLN(userAge); //prints out 20
Console.WrintLN(userEnglishGrade); //prints out 3

It looks almost the same as the out example above with a few exceptions. With ref , you are going to have to initialize the variable before calling the function whereas with out , you do so within the function. What ref does is that the address of the variable passed on is used to make the changes , which means the variable is directly updated within the function. If you have done any C programming before and it sounds similar to pointers , well then it is. In any case , for most of the time , you would probably be using the standard function with wither void or return.

Function Parameters Conclusion

Hope this clear up on the function parameters in C#. It isn’t as easy as my previous posts so if you didn’t get it the first time , don’t give up! Read , again and again a few more times and I am sure you will get it eventually. Cya!