typedef char *pStr1;
#define pStr2 char *;
pStr1 s1, s2;
#define pStr2 char *;
pStr1 s1, s2;
pStr2 s3, s4
In the above variable definitions, s1, s2, and s3 are all defined as char *, and s4 is defined as char, which
is not the pointer variable we expected. The fundamental reason is that #define is just a simple string replacement,
and typedef It is a new name for a type.
