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User defined functions

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Join Date: Sep 2008

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grisha83

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Junior Poster in Training

User defined functions

Sep 8th, 2008

Hello everyone,
Could you please explain to me how to write the user defined functions with multiple arguments? (specifically with 2 or 3 input arguments). And also, how to make one function to manipulate different data each time it is called? (for example area of bigger circle minus area of the smaller circle with one findArea function) To be specific, can you show me Prototype, function definition, and function call?
My C++ book doesn't explain it clearly.
Thank you very much

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Join Date: Sep 2004

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Narue

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Code Goddess

Re: User defined functions

Sep 8th, 2008

>Could you please explain to me how to write the
>user defined functions with multiple arguments?
There are three patterns for function parameters. First is a function with no parameters:

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void foo();
void foo();

No parameters is described in code using parentheses where there's nothing between them. Next is a single parameter, which is described in code using a variable declaration between the parentheses:

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void foo(int bar);
void foo(int bar);

The third pattern applies to all other numbers or parameters, just keep adding variable declarations and separate them with a comma:

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void foo(int bar, double baz, string meep);
void foo(int bar, double baz, string meep);

>how to make one function to manipulate different data each time it is called?
Pass in different values with each call. Those values will be copied into the variables you declare in the parameter list:

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#include <iostream>
 
int add_all ( int a, int b, int c )
{
  return a + b + c;
}
 
int main()
{
  std::cout<< add_all ( 0, 1, 2 ) <<'\n';
  std::cout<< add_all ( 3, 4, 5 ) <<'\n';
}
#include <iostream>

int add_all ( int a, int b, int c )
{
  return a + b + c;
}

int main()
{
  std::cout<< add_all ( 0, 1, 2 ) <<'\n';
  std::cout<< add_all ( 3, 4, 5 ) <<'\n';
}