This is a discussion on problem in pass by reference within the C++ Programming forums, part of the General Programming Boards category; solve...
Last edited by personal12; 09-25-2011 at 09:22 AM. Reason: not used
should be:Code:void main()
Now, your change function takes a pointer to int as an argument. Therefore, in the main function, you cannot pass number, but rather should pass &number to the change function. Note that we more typically refer to "pass by reference" as using a reference parameter, not a pointer parameter, even though passing a pointer has call by reference semantics with respect to what the pointer points to.Code:int main()
Incidentally, what is this program supposed to do?
Actually i have a assignment that asking me to get the array from a function then cout at another function.The user have to choose switch in order to get to the function
if i add & to the number.
it will give me address like-832455433;
When prefixed to an existing variable, & is the address of operator, eg:
When used with a function parameter or variable declaration, & indicates a reference:Code:int x, *p = &x;
Also note that this:Code:int x, &p = x; void somefunc(int &n);
is equivalent to this:Code:void change(int number)
which is why using &number works -- it creates a pointer, not a reference. As laserlight says, these are very similar things, but do confuse them as the syntax is non-compatible.Code:void change(int *number)
If you are trying to pass an array to another function, then (one of) the correct syntax(es) would be:
Very import exception here: do not use & on the array.Code:int myarray[arbitrary_size]; myfunc(myarray);
Now, you treat myarray as an array and print its contents.Code:void myfunc(int * myarray)
Merge posts Laser?
EDIT: Maybe you should consider this one as well. I think we have a homework spammer.
never mind .But please can someone tell me how come if i press 2 it will give me -89245435345 and how i can fix this.
you are not answering the question
> case 2:change(&a);break;
Passes a pointer to ONE integer.
> void change(int number)
Expects a pointer to TWO integers.
So yes, there is garbage to be found.
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It gives you that because a was not initialised, so when you pass a pointer to a, dereferencing the pointer gives you garbage. Furthermore, number is incorrect because a is a lone variable.Originally Posted by personal12
I cannot tell you how to fix this because I do not know what you are trying to do. Sure, you have stated what your assignment is about, but this does not tally with what I expect you to have written. Your change function does not change anything, so it has a lousy name. It looks like it is intended to print the first two elements of an array, yet you are trying to use it with a lone int variable.
You are not answering my questions either.Originally Posted by personal12
what do you mean by garbage to be found