Stack 和 Heap的区别

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Stack 和 Heap的区别

What is the stack? It's a special region of your computer's memory that stores temporary variables created by each function (including the main() function). The stack is a "LIFO" (last in, first out) data structure, that is managed and optimized by the CPU quite closely. Every time a function declares a new variable, it is "pushed" onto the stack. Then every time a function exits, all of the variables pushed onto the stack by that function, are freed (that is to say, they are deleted). Once a stack variable is freed, that region of memory becomes available for other stack variables. The advantage of using the stack to store variables, is that memory is managed for you. You don't have to allocate memory by hand, or free it once you don't need it any more. What's more, because the CPU organizes stack memory so efficiently, reading from and writing to stack variables is very fast. Another feature of the stack to keep in mind, is that there is a limit (varies with OS) on the size of variables that can be stored on the stack. This is not the case for variables allocated on the heap . https://www.gribblelab.org/CBootCamp/7_Memory_Stack_vs_Heap.html The heap is a region of your computer's memory that is not managed automatically for you, and is not as tightly managed by the CPU. It is a more free-floating region of memory (and is larger). To allocate memory on the heap, you must use malloc() or calloc() , which are built-in C functions. Once you have allocated memory on the heap, you are responsible for using free() to deallocate that memory once you don't need it any more. If you fail to do this, your program will have what is known as a memory leak . That is, memory on the heap will still be set aside (and won't be available to other processes). As we will see in the debugging section, there is a tool called valgrind that can help you detect memory leaks. Unlike the stack, the heap does not have size restrictions on variable size (apart from the obvious physical limitations of your computer). Heap memory is slightly slower to be read from and written to, because one has to use pointers to access memory on the heap. We will talk about pointers shortly. Unlike the stack, variables created on the heap are accessible by any function, anywhere in your program. Heap variables are essentially global in scope. When should you use the heap, and when should you use the stack? If you need to allocate a large block of memory (e.g. a large array, or a big struct), and you need to keep that variable around a long time (like a global), then you should allocate it on the heap. If you are dealing with realtively small variables that only need to persist as long as the function using them is alive, then you should use the stack, it's easier and faster. If you need variables like arrays and structs that can change size dynamically (e.g. arrays that can grow or shrink as needed) then you will likely need to allocate them on the heap, and use dynamic memory allocation functions like malloc() , calloc() , realloc() and free() to manage that memory "by hand". We will talk about dynamically allocated data structures after we talk about pointers. https://www.gribblelab.org/CBootCamp/7_Memory_Stack_vs_Heap.html http://net-informations.com/faq/net/stack-heap.htm 想要看到更多玮哥的学习笔记、考试复习资料、面试准备资料？想要看到IBM工作时期的技术积累和国外初创公司的经验总结？ 敬请关注： 玮哥的博客 —— CSDN的传送门 玮哥的博客 —— 的传送门 玮哥的博客 —— 博客园的传送门

heap和stack有什么区别

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heap和stack有什么区别

1.heap是堆，stack是栈。2.stack的空间由操作系统自动分配和释放，heap的空间是手动申请和释放的，heap常用new关键字来分配。3.stack空间有限，heap的空间是很大的自由区。在Java中，若只是声明一个对象，则先在栈内存中为其分配地址空间，若再new一下，实例化它，则在堆内存中为其分配地址。4.举例：数据类型 变量名；这样定义的东西在栈区。如：Object a =null; 只在栈内存中分配空间new 数据类型();或者malloc(长度); 这样定义的东西就在堆区如：Object b =new Object(); 则在堆内存中分配空间

heap是什么意思

提示：

heap是什么意思

heap
[英][hi:p][美][hip]
n.堆，堆积; 许多，大量; 破车;
vt.扔成一堆; 完全填满，灌满; 大量或奢侈的赠予;
第三人称单数：heaps
复数：heaps
现在进行时：heaping
过去式：heaped
过去分词：heaped
例句
1.Where'd you find that heap?
这破车哪儿找来的？
2.Get this bloody heap going.
拿上这堆该死的东西走吧。

stack 和heap都是堆积的意思，两者有区别吗

提示：

stack 和heap都是堆积的意思，两者有区别吗

在计算机语言中，stack 表示栈，heap表示堆，这是两个概念。
栈stack是计算机系统提供的具有后进先出特点的数据结构，
而堆heap是函数库提供的内部结构，为分配新内存空间服务的。

在日常英语中，二者都指堆积（动词）和一堆（名词），但是
heap 通常指杂乱的、呈小山状的一堆东西，如：Now， the house is a heap of rubble（现在，房子成了一堆瓦砾）。
stack通常是整齐的一叠，指扁平物体叠放起来，如：a neat stack of dishes（整齐的一叠盘子）。

堆(heap)和栈(Stack)的区别是什么？为什么平时都把堆栈放在一起讲？

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堆(heap)和栈(Stack)的区别是什么？为什么平时都把堆栈放在一起讲？

将堆跟栈放在一起将是因为两者都是存储数据的方式。区别如下： 一、主体不同 1、堆：是计算机科学中一类特殊的数据结构的统称。堆通常是一个可以被看做一棵完全二叉树的数组对象。 2、栈：又名堆栈，它是一种运算受限的线性表。限定仅在表尾进行插入和删除操作的线性表。 二、特点不同 1、堆：堆中某个节点的值总是不大于或不小于其父节点的值；堆总是一棵完全二叉树。 2、栈：是一种只能在一端进行插入和删除操作的特殊线性表。它按照先进后出的原则存储数据，先进入的数据被压入栈底，最后的数据在栈顶。 三、作用不同 1、堆：堆是非线性数据结构，相当于一维数组，有两个直接后继。 2、栈：可以用来在函数调用的时候存储断点，做递归时要用到栈。 参考资料来源：百度百科-堆 参考资料来源：百度百科-栈

堆(heap)和栈(Stack)的区别是什么？为什么平时都把堆栈放在一起讲？

提示：

堆(heap)和栈(Stack)的区别是什么？为什么平时都把堆栈放在一起讲？

堆和栈的区别：
　　一、堆栈空间分配区别：
　　1、栈（操作系统）：由操作系统自动分配释放
，存放函数的参数值，局部变量的值等。其操作方式类似于数据结构中的栈；
　　2、堆（操作系统）：
一般由程序员分配释放，
若程序员不释放，程序结束时可能由os回收，分配方式倒是类似于链表。
　　二、堆栈缓存方式区别：
　　1、栈使用的是一级缓存，
通常都是被调用时处于存储空间中，调用完毕立即释放；
　　2、堆是存放在二级缓存中，生命周期由虚拟机的垃圾回收算法来决定（并不是一旦成为孤儿对象就能被回收）。所以调用这些对象的速度要相对来得低一些。
　　三、堆栈数据结构区别：
　　堆（数据结构）：堆可以被看成是一棵树，如：堆排序；
　　栈（数据结构）：一种先进后出的数据结构。