在C中添加unsigned long和int

Question

    int meta_size = 24;
    node_t* prev;

    printf("%lx, ", prev + meta_size );
    printf("%lx, ", prev); 
    printf("%lx, ", meta_size);

输出：1519240,1519000,18 这是怎么回事？

Answer 1

Prev是一个单元化指针，它包含（一个随机的，因为它没有被初始化）内存地址。

printf("%lx, ", prev + meta_size );//Prints the memory address prev is pointing to + (sizeof(node_t) * meta_size)
printf("%lx, ", prev);             //Prints the memory address prev is pointing to
printf("%lx, ", meta_size);        //Prints meta_size, 18 is 24 in hexidecimal, because of the 'x' in %lx 

但是，前两行是未定义的行为，因为指针应使用％p

打印

Answer 2

如果你做sizeof(node_t)我很确定你会获得10.