Thokchom questions

• Why does /*comment*/ inserted randomly inside C code works in some places only,not everywhere?
• What happens to the increment of "b" in "return b++" ,if used in a function?
• What exactly is redefinition of a macro in C? What's the point, given so many restrictions on it?
• Is the NULL pointer implicitly converted to type (int*) when we use "if(ptr==NULL)" for an integer pointer ptr?
• For function pointer "fptr",why is value of "fptr" and *fptr same?What *fptr even mean?I only knew (*fptr)() or fptr() [duplicate]
• Why is absence of array index in "extern char name[]" not affecting strlen(name) but causing error for sizeof(name)?
• Why is the %n format specifier working normal for all scanf() statements but storing one less in the first one?
• Why printf("%s",(char[]){'H','i','\0'}) works as printf("%s","Hi"), but printf("%s",(char*){'H','i','\0'}); fails? [duplicate]
• Why is 'continue' statement ignoring the loop counter increment in 'while' loop, but not in 'for' loop?
• What is the difference between memcpy() and strncpy() given the latter can easily be a substitute for the former?

Thokchom answers