1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 | #include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
// Q: Can I avoid writing 'struct ▒' everywhere?
// A: Use a typedef.
// struct Point { int x; int y; };
// struct Point p = { .x = 5, .y = 6};
//
// .... equivalent to ...
//
// typedef struct { int x; int y; } Point;
// Point p = { .x = 5, .y = 6};
//
// and likewise for a union or enum.
typedef struct {
union {
int as_int;
double as_double;
};
enum NumberType {
NUMBER_INT,
NUMBER_DOUBLE
} type;
char* name;
} Number; // << SEMICOLON <<
// Type name is now just 'Number' instead of 'struct Number'
void print_number(Number n) {
if(n.type == NUMBER_INT) {
printf("%s: %d\n", n.name, n.as_int);
}
else if(n.type == NUMBER_DOUBLE) {
printf("%s: %f\n", n.name, n.as_double);
}
else {
assert(false); // Unexpected value of type_of_n
}
}
int main(int argc, char* argv[]) {
Number n = {.as_int = 5,
.type = NUMBER_INT,
.name = "Eff Eye Vee Yee" };
print_number(n); // Value and type are now encapulated in one variable.
return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */
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