Macro definition simply string substitution, the pretreatment is completed, the process is typedef at compile time, it is not as simple substitution, but to re-order the type specifier. Named has a function type definition identifiers described.
#include <stdio.h> #include <the iostream> #define PIN1 char * typedef char * PIN2; int main () { // Use #define equivalent: char * x, y; x is a char that is a pointer type, and y is a char type PIN1 x, y; // using typedef equivalent: char * x, char * y ; x is a char that is a pointer type, and y is char pointer type PIN2 A, B; the printf ( " By #define: % D% D \ n-\ n- " , the sizeof (X), the sizeof (Y)); the printf ( " By typedef:% D% D \ n-\ n- " , the sizeof (A), the sizeof (B)); System ( "pause"); return 0; }
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