CODEWITHSUNDEEP
c++cgccg++
Maroun
Maroun

Reputation: 96016

Why calling a function that accepts no parameters with a parameter compiles in C but doesn't in C++

Suppose I have this function:

void func() {}

When I call func with some parameters (e.g. func(132)), the C++ compiler yields an error, while the C compiler doesn't.

What is the difference between the two compilers in this case? And what advantages/disadvantages the C++ has by arising this error?

Upvotes: 16

Views: 710

Answers (2)

Dietrich Epp
Dietrich Epp

Reputation: 213837

There are no advantages or disadvantages. C supports this for compatibility with K&R C from the 1980s. You might like this feature if you are still using code you wrote in the 1980s. You might dislike this feature if you want better diagnostics from your compiler.

void func();

In C, this means that func takes unspecified parameters.

If you need to specify that the function takes no parameters, write it this way:

void func(void);

In C++ the two prototypes are the same. (In C, only the second one is a prototype.) If you compile with GCC/Clang's -Wstrict-prototypes option, you will get warnings for using void func(); in C, as you should.

This is only about function declarations. In both languages, the following function definitions are the same:

// These two are the SAME
void func() { }
void func(void) { }

// These two are DIFFERENT
void func();
void func(void);

Upvotes: 36

paxdiablo
paxdiablo

Reputation: 882726

In C++, that function has no arguments. In C, it means an indeterminate number of arguments.

This is a holdover from the very earliest days of C where every function returned an int and it was much more relaxed about arguments being passed.

Upvotes: 8

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