Is there any issue if I take a parameter as a value that is coming as a reference?

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I have a message. Passing the message as a reference to a function. Within the function, passing the message to other function that taking the message as a value. Program is running fine and giving the expected output. Is there any issue to do like this?

Example:

C++

#include <iostream>
#include <string>

void displayMessage(std::string str) //taking parameter as a value
{
    std::cout<<str<<std::endl;
}
 
void showmessage(std::string &str) //taking parameter as a reference
{
   std::cout<<str<<std::endl;
 
   displaymessage(str);
}


int main()
{
   std::string str="Hello" ;
   showmessage(str);
   return 0;
}

What I have tried:

I have a message. Passing the message as a reference to a function. Within the function, passing the message to other function that taking the message as a value.

Posted 25-Dec-21 15:53pm

Member 14036158

Updated 25-Dec-21 17:09pm

k5054

v3

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k5054 · Accepted Answer · 2021-12-25T17:09:00

There are no issues with your code. When you call dislplaymessage() from within showmessage(), a copy of the object referenced by shomessage() argument str is created, nota copy of the reference. This can be demonstrated simply:

C++

#include <iostream>

class C
{
public:
    // constructor
    C(){ 
        std::cout << "constructor\n";
    }

    // copy constructor
    C(const C &other) {
        std::cout << "copy constructor\n";
    }
};


void foo(C c)
{
    std::cout << "foo\n";
}

void bar(C& c)
{
    std::cout << "bar\n";
    foo(c);
}

int main()
{
    C c;

    bar(c);
}

produces the output

constructor
bar
copy constructor
foo