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 | #include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include "log_macros.h"
// BAD WAY #1: use raw integers to indicate type. TERRIBLE!!!
union Value {
int as_int;
char* as_string;
};
// A union object can contain only one of the fields; they share the same space.
void print_element(union Value the_value, int type_of_value) {
if(type_of_value == 0) { // We cannot know type in the_value without another parameter.
printf("the_value is %d\n", the_value.as_int);
}
else {
printf("the_value is %s\n", the_value.as_string);
}
}
int main(int argc, char* argv[]) {
union Value the_value = { .as_int = 5 };
the_value.as_int = 7;
print_element(the_value, 0); // 0 means it's an int (TERRIBLE)
the_value.as_string = "apple";
print_element(the_value, 1); // 1 means it's a string (TERRIBLE)
return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */
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