C default arguments?

Question

Is there a way to specify default arguments to a function in C?

Answer 1

The short answer is NO.

You must mangle the function name if only in C.

In C++, yes, you can declare default arguments.

Note that in the C++ code snippets below, the same function is used whereas in the

C code, the function has to be declared (with the name mangled) multiple times.

The only problem with the default arguments in C++ is you cannot omit the first argument

but supply the second. Once you default the argument, any parameters after that must have

default values.

Here is some code:

//======================= printChar.c ===================================

#include <stdio.h>

/* master parent function */

printChar( char ch, int n)

{

int i;

for (i=0; i<n; i++)

{

printf("%c",ch);

}

printf("\n");

}

/* defaults the char to star asterisk */

printStar( int n)

{

printChar('*',n);

}

/* defaults the count to 10 */

print10( char ch)

{

printChar(ch,10);

}

int main()

{

printChar('!',5); // prints 5 exclamation points

printChar('$',7); //prints 7 dollar signs

printChar('#',6); //prints 6 pound signs

printStar(10); //prints 10 star asterisks: note that the function name is mangled

print10('@'); // prints 10 AT symbols using a technically different function that calls the parent

}

================ printChar.cpp ==========================

#include <stdio.h>

#define DEFAULT_CHAR ('*')

/* master parent function */

printChar( char ch='*', int n=10)

{

int i;

for (i=0; i<n; i++)

{

printf("%c",ch);

}

printf("\n");

}

int main()

{

printChar('!',5); //prints 5 exclamation points

printChar('$'); //prints 10 dollar signs

printChar(DEFAULT_CHAR,7); //prints 7 star asterisks: note the first parameter must be passed

printChar('#',2); // prints 2 pound signs

printChar(); //prints 10 star asterisks

}