How to Exit a Method without Exiting the Program

Question

I am still pretty new to C  and am having a difficult time getting used to it compared to C CPP    How do you exit a function on C  without exiting the program like this function would   if  textBox1 Text          textBox1 Text    String Empty    textBox1 TextLength    0      textBox3 Text      -  Listbox is Empty     r n   System Environment Exit 0     This will not allow return types and if left alone it will keep going on through the function unstopped  Which is undesirable

User · Accepted Answer

There are two ways to exit a method early (without quitting the program):

Use the return keyword.
Throw an exception.

Exceptions should only be used for exceptional circumstances - when the method cannot continue and it cannot return a reasonable value that would make sense to the caller. Usually though you should just return when you are done.

If your method returns void then you can write return without a value:

return;

Specifically about your code:

There is no need to write the same test three times. All those conditions are equivalent.

You should also use curly braces when you write an if statement so that it is clear which statements are inside the body of the if statement:

if (textBox1.Text == String.Empty)
{
    textBox3.Text += "[-] Listbox is Empty!!!!\r\n";
}
return; // Are you sure you want the return to be here??

If you are using .NET 4 there is a useful method that depending on your requirements you might want to consider using here: String.IsNullOrWhitespace.
You might want to use Environment.Newline instead of "\r\n".
You might want to consider another way to display invalid input other than writing messages to a text box.

User · Answer

If the function is a void  ending the function will return  Otherwise  you need to do an explicit return someValue  As Mark mentioned  you can also throw an exception  What s the context of your question  Do you have a larger code sample with which to show you some ways to exit the function

User · Answer

John  Earlz and Nathan  The way I learned it at uni is  functions return values  methods don t  In some languages the syntax is was actually different  Example  no specific language    Method SetY int y      Function CalculateY int x  As Integer       Most languages now use the same syntax for both versions  using void as a return type to say there actually isn t a return type  I assume it s because the syntax is more consistent and easier to change from method to function  and vice versa

User · Answer

The basic problem here is that you are mistaking System Environment Exit for return

User · Answer

In addition to Mark s answer  you also need to be aware of scope  which  as in C C    is specified using braces  So   if  textBox1 Text          textBox1 Text    String Empty    textBox1 TextLength    0      textBox3 Text      -  Listbox is Empty     r n   return    will always return at that point  However   if  textBox1 Text          textBox1 Text    String Empty    textBox1 TextLength    0        textBox3 Text      -  Listbox is Empty     r n       return      will only return if it goes into that if statement

User · Answer

I would use return null  to indicate that there is no data to be returned

[c#] How to Exit a Method without Exiting the Program?

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