Re: Porting C to C++
Paul wrote [5/22/2009 1:43 PM]:
I am porting a piece of code from C to C++. The C code has a macro
like this:
#define MALLOC(p, b, s) {if ((b) > 0) { \
p= malloc(b); if (!(p)) { \
fprintf(stderr, "memory allocation error:
%s\n", s); \
exit(0);}} else p= NULL;}
the g++ compiler complains about "invalid conversion from void* to"
xxx* because of the lack of a cast in front of p.
Is there a way to fix this macro so that it can work in C++?
The missing piece of information is the type of p. Whenever the code
is identical except for type information, think templates.
template <class T>
T* MallocHelper(T* p, size_t b, const char *s)
{
if ( b > 0 )
{
p = reinterpret_cast<T *>(malloc(b));
if ( ! p )
{
fprintf(stderr, "memory allocation error: %s\n", s);
exit(0);
}
}
else
p = 0;
return p;
}
#define MALLOC(p, b, s) ((p) = MallocHelper((p), (b), (s)))
int main(int argc, char *argv[])
{
char *p = 0;
MALLOC(p, 10, "main");
strcpy(p, "hello");
printf("%s\n", p);
return 0;
}
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