Question

As noted in this chapter, C and C++ make a distinction between a declaration and a definition.
Which of the following are declarations only and which are definitions? (a) char * name; (b) typedef int * IntPtr; (c) struct rec;
(d) int gcd(int,int); (e) double y; (f) extern int z;

Answer 1

Answer :

a) char *name;

Here declaration and definitions both are happening. Name and data type of variables are sent to the compiler and memory is allocated.

d) int gcd(int,int);

Only declaration is done. Name of the function and data type, and number of arguments are  sent to the compiler but no memory is allocated. That's why it is not defined.

f) extern int z;

Here also name of the variable and data type is sent to the compiler. Memory is not allocated for this. Hence only declaration is happening.

e) double y;

Both declaration and definitions are happening. Name and data type of the variable along with memory allocation is sent to the compiler.