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John Phung
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 Posted: Thu Feb 26, 2004 10:54 pm Post subject: passing data structures into a function |
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How do you pass a data structure into a function? I'm using c++ to solve the
producer and consumer problem and so far, I cannot find an example of how to do
this. So, if anyone can help me, that would be nice.
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John Harrison
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| Posted: Thu Feb 26, 2004 10:58 pm Post subject: Re: passing data structures into a function |
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"John Phung" <jphung (AT) rohan (DOT) sdsu.edu> wrote
| Quote: | How do you pass a data structure into a function? I'm using c++ to solve
the
producer and consumer problem and so far, I cannot find an example of how
to do
this. So, if anyone can help me, that would be nice.
|
It's not difficult, you can pass a data structure into a function using
exactly the same methods as you would pass a simple type.
DataStructure my_data_structure;
some_function(my_data_structure);
some_function could be declared like this
void some_function(DataStructure a_data_structure);
like this
void some_function(DataStructure& a_data_structure);
or like this
void some_function(const DataStructure& a_data_structure);
depending on exactly what you are trying to do.
But really your options are exactly the same as if you are trying to pass an
int into a function.
john
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Mike Wahler
Guest
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| Posted: Thu Feb 26, 2004 11:01 pm Post subject: Re: passing data structures into a function |
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"John Phung" <jphung (AT) rohan (DOT) sdsu.edu> wrote
| Quote: | How do you pass a data structure into a function? I'm using c++ to solve
the
producer and consumer problem and so far, I cannot find an example of how
to do
this. So, if anyone can help me, that would be nice.
|
#include <iostream>
// define a structure
struct X
{
int m;
};
// a function with a structure as a parameter
void function(X arg)
{
std::cout << arg.m << 'n'; // prints 42
}
int main()
{
X obj = {42}; // create an instance of type 'X'
function(obj); // pass 'X' to 'function()'
return 0;
}
If the structure is 'large', it's usually better to
pass by reference:
void function(X& arg)
{
// etc
}
And if the function doesn't modify the argument, pass
by const reference:
void function(const X& arg)
{
// etc
}
In all cases above, the calling syntax is the same.
Another way is by using a pointer parameter, which
does change the calling syntax:
void function (X *arg) // or const X *arg if applicable
{
// etc
}
call with:
X obj = {42};
function(&obj);
Which C++ book(s) are you reading?
-Mike
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Karl Heinz Buchegger
Guest
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| Posted: Thu Feb 26, 2004 11:08 pm Post subject: Re: passing data structures into a function |
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John Phung wrote:
| Quote: |
How do you pass a data structure into a function? I'm using c++ to solve the
producer and consumer problem and so far, I cannot find an example of how to do
this.
|
????
What books are you using?
| Quote: | So, if anyone can help me, that would be nice.
|
struct test
{
int a;
int b;
}
void foo( test Arg )
{
std::cout << Arg.a;
std::cout << Arg.b;
}
int main()
{
test MyVar;
MyVar.a = 4;
MyVar.b = 8;
foo( MyVar );
}
--
Karl Heinz Buchegger
[email]kbuchegg (AT) gascad (DOT) at[/email]
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