Some Interesting facts about default arguments in C++
Predict the output of following C++ programs.
1)
#include <iostream>
void init( int a=1, int b=2, int c=3);
int main()
{
init();
return 0;
}
void init( int a=1, int b=2, int c=3)
{
std::cout << a << ' ' << b << ' ' << c;
}
|
The above program looks correct at first glance but will fail in compilation. If function uses default arguments then default arguments can’t be written in both function declaration & definition. It should only be in declaration, not in definition.
The following program is now correct.
#include <iostream>
void init( int a=1, int b=2, int c=3);
int main()
{
init();
return 0;
}
void init( int a, int b, int c)
{
std::cout << a << ' ' << b << ' ' << c;
}
|
2)
#include <iostream>
void init( int =1, int =2, int =3);
int main()
{
init();
return 0;
}
void init( int a, int b, int c)
{
std::cout << a << ' ' << b << ' ' << c;
}
|
If you closely observe function prototype then it looks like an error but it isn’t actually. Variable names can be omitted in default arguments.
Last Updated :
14 Dec, 2022
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