问题描述
说我有一个void *命名PTR。我应该去究竟如何使用PTR来存储一个int？是否足以写
Say I have a void* named ptr. How exactly should I go about using ptr to store an int? Is it enough to write
ptr = (void *)5;
如果我要保存5号？还是我对malloc的东西保存？
If I want to save the number 5? Or do I have to malloc something to save it?
推荐答案
您正在铸造 5 是一个无效的指针的然后分配到 PTR 。
You're casting 5 to be a void pointer and assigning it to ptr.
现在 ptr指向的内存地址0x5的
如果这实际上是你想要做什么..嗯，是啊，这工作。你......可能不希望这样做。
If that actually is what you're trying to do .. well, yeah, that works. You ... probably don't want to do that.
当你说存储一个int我会想你的意思是你想实际整型值5存储在内存指向的无效* 。只要有足够的分配内存（的sizeof（INT）），你可以用铸造这样做...
When you say "store an int" I'm going to guess you mean you want to actually store the integer value 5 in the memory pointed to by the void*. As long as there was enough memory allocated ( sizeof(int) ) you could do so with casting ...
void *ptr = malloc(sizeof(int));
*((int*)ptr) = 5;
printf("%d\n",*((int*)ptr));
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