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

如果你这样做 sizeof(node_t) 我很确定你会得到 10。

Answer 2

Prev是一个初始化指针，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，因为指针应该用 %p 打印

在C中添加unsigned long和int

Addition of unsigned long and int in C

c

hex

unsigned-integer