Is Array in C++ passed by reference or value?

Edit: or should I wait for your tutorial..?

__________________

---

Arrays in C++ are passed by reference when used as arguments to functions, just like in C, though it is often done via pointer notation:
You can also do the following:
For some reason, even though the data type is char[], arrays are one bit of C++ that still prefers things to be associated with the variable rather than with the data type, which the creator of C++ didn't want. In C, the idea is that string_to_print is a pointer to a char in memory or a pointer to an array of chars in memory. In C++, the idea is that string_to_print is a char pointer (like in C) or an array of chars in itself. However, one can still use pointer notation for referencing things in arrays, though there are restrictions, such as you can't change where an array begins (understandable since it will screw up the idea that array_a[42] would still have 42 elements, but the data used by those 42 elements would be shifted).

__________________

---

So, there's only one type of Array in C++ ??? char ??? If that so, then you need to parse everything out before storing them in arrays then...?? *That's d**n difficult* Should create a method for that one first then if it does so...

Can I do this in C++:

__________________

---

LOL char is just the data type of the array.

As for your function, it would need a name first and a few other things would need to be done. First of all, I had planned on referencing the fact that arrays in C and C++ are not like in Java, where you can simply use <array_name>.length to get the number of elements in the array. In C and C++, you need to use "sizeof(<array_name>) / sizeof(*<array_name>). However, this does not work with dynamic arrays or strings ("malloc"/"calloc"/"realloc" in C, "new <data_type>[num_elements]" in C++). Therefore, when using dynamic arrays, you must keep track of things yourself, usually the length of the array/string is most important. Also, you wouldn't use "char.length" in Java, would you? The same basic tools that apply in Java also apply in C++. However, things like operator precedence are a bit different. As a result, I've learned to put parentheses around certain things like bitwise operations in an if statement:
if (1 & 3 == 1)
would be false in Java because it evaluates it like this:
"if (1 & (3 == 1))" is "if (1 & false)" which is like "if (0)".

The solution is to do this:
if ((1 & 3) == 1)

Now as for your function:
A few strange things went on there, right? Let's start with the basics of it:
That denotes the beginning of a function named "some_function" with no return value because the return type is "void". There are no arguments to the function.
(In C99 (not C++), it is required, I believe, to specify "int main (void)" rather than "int main ()" when there are meant to be no command-line arguments to the program.)

What is this one about? Well, that just says to create a char array named "string_to_print" with a maximum capacity of 256 characters.

This one is a normal loop. It goes from 1 to the 2 less than length of the array, incrementing by 1 every time. Why things start at 1 will be discussed next.

This one is unusually strange looking! Why not just use "i" rather than "i & 255" for example? The answer is simple. If we used "i", our string would never terminate (no null terminator). The "i & 255" ensures that it does by doing a bitwise AND. Also, if we had used "i = 0" instead of "i = 1", our string would have terminated immediately because that would mean the null terminator stops the string right at the beginning. More on the null terminator after the next code segment.

Also, there is for a good reason for the bitwise AND there. For one thing, using "i % 256", where 256 is the number of characters in the string, including the null terminator, would be a pain. There is an old trick where if the value that you are modding by is a power of two, you can just use a bitwise AND to do the same thing as long as you subtract 1 from the power of two. For example, to do 9 % 4, you could just say 9 & 3, which in binary is 1001 AND 0011, which is 0001 (1 in decimal). Is that correct? Let's see! 9 / 4 = 2, remainder = 1 (4 * 2 = 8, 8 + 1 = 9). It was used for efficiency in the days of slower computers and I'm not sure how efficient it makes things anymore, but I still use it.

This seems pretty straightforward, right? I mean, it makes the last element 0, but why is it there? When dealing with character arrays as strings, the last element MUST be a null terminator, which is character code 0 or the special escape code '\0'. The reason why is because there is no other way to determine where a string ends without adding some overhead to the code. Not only that, but it is very convenient when you need to truncate a string at the end so that only the beginning and part of the rest of the string is left.

The rest is easy to figure out.

To summarize:

• There is no such thing as being crazy with parentheses in C++ or C, especially when working with "macros", where parentheses can make or break your macro's intended behavior.
• C++ notation for constructs such as loops and branching are similar to, if not exactly like, the equivalent constructs in other languages such as Java.
• When strings are actually character arrays, there must be one extra element allocated for the null terminator.
• sizeof(<array_name>) / sizeof(*<array_name>) gets the length of an array that is not dynamic.
• bitwise operators can be of use possibly

I hope this helps.

__________________

---

Thanx a lot rpgfan, I think this should be an official tutorial or something
I really do understand the difference now.. One more thing though,

what does "&" (without quote) means in C++ or C languages???

__________________

---

Its official name in C and C++ is the "Bitwise AND" operator

If you've ever studied the Binary (Base-2) number system, then you've probably a good idea what AND does when you compare two 'bits'

for example, take these numbers in decimal (Base 10), 9 and 7

When you perform a Bitwise AND on these two numbers, the effect of the operation only makes sense when you view their binary representation

9 in binary is 1001
7 in binary is 0111

so 7 AND 9 yields 0001 (which is 1 in decimal)

(If you're not too sure on the link between computers and binary, or how to convert decimal to binary, then i'd suggest doing some googling )


Note, & is not to be confused with &&, which is the Logical AND operator... the use of which generally involves comparisons.

__________________

---

Can you please explain me how does this example yields to 0001? do you substract them? Well, now I'm learning Discrete Math, but I never knew this.. XD

__________________

---

Look at the vertical alignment of each digit on its own..

the result of AND only yields a '1' when both sides are a '1'


This kind of arithmetic is somewhat analogous to the way you learn basic math at primary school.. ie, isolating each digit, and performing the given operation. eg, how would you add the numbers 140 and 612 together? although, unlike Bitwise-AND, the decimal math you learn in primary school has you worrying about digits "carrying over" aswell

__________________

---

Thanx a lot buddy, I finally got it!! There's connection with symbolic logic right? Where 'true' and 'true' is 'true' while 'true' and 'false' is 'false' ???

__________________

---

The idea is the exactly the same, yes. Although Conditional logic is used for an entirely different reason in C/C++ than bitwise logic..

One way to look at it, is that everything in your computer boils down to '1's and '0's ( or 'on'/'off' .. or 'true'/'false' ..etc).. however, different circuits inside the system use the status of a bit (or of a series of bits) for different purposes.. You have some circuits which are designed for arithmetic, where bitwise logic comes into play, and other circuits which are designed for decision-making, where conditional logic is used.
Of course, its a bit more complicated than that, but thats the 'gist' of it.

__________________

---