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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

#define log_addr(n) printf("%s == %p\n", #n, (void*)(n))
#define log_int(n) printf("%s == %x\n", #n, n)
#define log_str(n) printf("%s == \"%s\"\n", #n, n)

int main(int argc, char* argv[]) {
    int n = 0x1234;
    int* a_n = &n;
    const char* str = "Hello";
    char str2[] = "World";

    void* a_unknown = a_n;
    log_addr(a_n);
    log_addr(str);
    log_addr(str2);
    log_addr(a_unknown);

    a_unknown = str2;
    log_addr(a_unknown);
    
    const void* a_unknown_constant = str;
    log_addr(a_unknown_constant);
    a_unknown_constant = a_n;
    log_addr(a_unknown_constant);

    int* a_unknown_as_int = a_unknown;
    log_int(*a_unknown_as_int);
    a_unknown = a_n;
    char* a_unknown_as_str = a_unknown;
    log_str(a_unknown_as_str);

    // you cannot directly dereference a void* address
    // gives a compiler error
    //log_int(*a_unknown);
    
    //log_addr(a_unknown + 10);
    log_addr(a_n + 10);

    if (a_unknown < a_unknown_constant) {
        printf("a_unknown is smaller\n");
    }

    // bad cast: discards const qualifier
    // we could write this assigbment without the cast and it would
    // be validated by the compiler
    a_unknown = (void*) str;
    log_addr(a_unknown);

    // bad: unneeded cast caused an "accidental" wrong assignment
    // its easy when using unneeded casts to do an assignment that is
    // invalid
    a_unknown_as_int = (int*) str2;
    log_addr(a_unknown_as_int);
    

    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */

© Copyright 2024 Alexander J. Quinn & David Burnett         This content is protected and may not be shared, uploaded, or distributed.