calloc和malloc_malloc（）vs calloc（）– C中的malloc（）和calloc（）之间的区别

清疚 2022-12-07 12:58 168阅读 0赞

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calloc和malloc

Here in this tutorial you will learn about difference between malloc() and calloc() in C.

在本教程的这里，您将学习C语言中malloc()和calloc()之间的区别。

We all know that memory is available in limited size only, so it becomes important for us to use it efficiently. If we are writing a program that uses too much of memory resulting in wastage of memory or conversely if we allocate too little memory so that we can’t store enough information, that means we are not sure of the amount of data to be stored. In such cases, [dynamic memory allocation][] comes to the rescue, where our program is capable to allocate whatever amount of memory it needs during the run-time of programs.

我们都知道，内存仅在有限的大小内可用，因此有效使用内存对我们来说很重要。 如果编写的程序使用过多的内存导致内存浪费，或者相反，如果分配的内存太少以致于我们无法存储足够的信息，则意味着我们不确定要存储的数据量。 在这种情况下， [动态内存分配便][dynamic memory allocation]可以解决，我们的程序能够在程序运行时分配所需数量的内存。

Now the question arises is that how can we achieve dynamic memory allocation in our programs?

现在出现的问题是，如何在程序中实现动态内存分配？

In the C Language, we have predefined functions like calloc() and malloc() defined under the stdlib.h header file that can be used to allocate memory during the runtime of a program.

在C语言中，我们在stdlib.h头文件下定义了预定义的函数，如calloc()和malloc()，可在程序运行时用于分配内存。

Let’s understand this awesomely useful function with simple examples:

让我们通过简单的示例来了解这个非常有用的功能：

### malloc()函数 **(**malloc() Function**)** ###

malloc() is an abbreviation for **m**emory-**alloc**ation. It is a predefined function defined in the stdlib.h header file. It is used to allocate memory during the runtime of a program. The memory allocated is uninitialized that means it has garbage values.

malloc()函数是用于**米** emory- **的alloc**通货膨胀的缩写。 它是在stdlib.h头文件中定义的预定义函数。 它用于在程序运行时分配内存。 分配的内存是未初始化的，这意味着它具有垃圾值。

**Syntax:**

**句法：**

ptr = (type*) malloc (size in bytes to be allocated)

The malloc() function takes size in bytes to be allocated as argument. If the memory allocation is successful, it returns a [void pointer][] to the beginning of the allocated memory. This void pointer can be type-casted to any type of pointer. If the memory allocation fails due to reasons like insufficient memory, the malloc() function returns a [NULL pointer][].

malloc()函数采用字节大小作为参数分配。 如果内存分配成功，它将返回一个[空指针][void pointer] ， [指向][void pointer]已分配内存的开头。 可以将这个void指针类型转换为任何类型的指针。 如果由于内存不足等原因导致内存分配失败，则malloc()函数将返回[NULL指针][NULL pointer] 。

It is the responsibility of the programmer to deallocate the allocated memory before program ends using free() or realloc() functions.

程序员有责任在程序结束之前使用free()或realloc()函数释放已分配的内存。

**C Program Implementation of malloc() Function**

**malloc()函数的C程序实现**

#include <stdio.h>  
    #include <stdlib.h>
     
    int main()  
    {
        /* The memory allocated by malloc contains garbage value */   
        /* allocates 10*sizeof(int) = 40 bytes of memory */  
        int *ptr1 = (int*)malloc( 10 * sizeof(int));      
        
        /* allocates 8*sizeof(char) = 8 bytes of memory  */  
        char *ptr2 = (char*)malloc( 8 * sizeof(char)); 
        
        if(ptr1)   
        { 
            printf("Memory allocation successful !!");  
            
        }  
        else  
        {  
            printf("Memory allocation failed !!");  
            
        }  
        
        free(ptr1);  
        free(ptr2);  
        return 0;  
    }

**Output**

**输出量**

*Memory allocation successful !!*

*内存分配成功！*

### calloc()函数 **(**calloc() Function**)** ###

calloc() is an abbreviation for **c-**contiguous **a-**allocation. It is an advancement over the malloc() function. It is used to allocate multiple blocks of memory of the same size dynamically. The memory is initialized with zero.

calloc()是**c-**连续**a-**分配的缩写。 它是对malloc()函数的改进。 它用于动态分配相同大小的多个内存块。 内存初始化为零。

**Syntax:**

**句法：**

ptr = (type*) calloc (number of blocks , the size of blocks in bytes to be allocated)

The calloc() function takes two arguments. First argument is the number of blocks of memory to be allocated and the second argument is used to define the size of blocks in terms of bytes. If the memory allocation is successful, it returns a void pointer to the beginning of the allocated memory. This void pointer can be type-casted to any type of pointer. If the memory allocation fails due to reasons like insufficient memory, the calloc() function returns a NULL pointer.

calloc()函数采用两个参数。 第一个参数是要分配的内存块数，第二个参数用于以字节为单位定义块的大小。 如果内存分配成功，它将返回一个空指针，指向已分配内存的开头。 可以将这个void指针类型转换为任何类型的指针。 如果由于内存不足等原因而导致内存分配失败，则calloc()函数将返回NULL指针。

It is the responsibility of the programmer to deallocate the allocated memory before program ends using free() or realloc() functions.

程序员有责任在程序结束之前使用free()或realloc()函数释放已分配的内存。

**C Program Implementation of calloc() Function**

**C语言实现calloc()函数**

#include <stdio.h>  
    #include <stdlib.h>  
     
    int main()  
    {  
        /* The calloc function initialize the memory with 0 */   
        /* allocates 4 blocks of memory with size of int */  
        int *ptr1 = (int*)calloc(4, sizeof(int));      
        
        /* allocates 8 blocks of memory with size of float */  
        float *ptr2 = (float*)calloc(8, sizeof(float));   
        
        if(ptr1)   
        {  
            printf("The values are:\n");  
            for(int i=0;i<4;i++)  
            {  
                /* printing the data of memory-allocated */  
                printf("Memory block %d : %d \n",i+1,*(ptr1+i));   
            }  
        }  
        else  
        {  
            printf("Memory allocation failed !!");  
        } 
        
        free(ptr1);  
        free(ptr2);  
        
        return 0;  
    }

**Output**

**输出量**

*The values are:* *Memory block 1 : 0*  *Memory block 2 : 0*  *Memory block 3 : 0*  *Memory block 4 : 0*

*值为：* *内存块1：0* *内存块2：0* *内存块3：0* *内存块4：0*

## malloc()vs calloc()– malloc()和calloc()之间的区别 **(**malloc() vs calloc() – Difference between malloc() and calloc()**)** ##

<table> 
 <tbody> 
  <tr> 
   <td><strong>Parameters</strong></td> 
   <td><strong>malloc()</strong></td> 
   <td><strong>calloc()</strong></td> 
  </tr> 
  <tr> 
   <td>Abbreviated for</td> 
   <td><strong>m-</strong>memory<strong>,&nbsp; alloc-</strong>allocation</td> 
   <td><strong>c-</strong>contiguous<strong>,&nbsp; alloc-</strong>allocation</td> 
  </tr> 
  <tr> 
   <td>Syntax:</td> 
   <td>(void*) malloc (n * size in bytes)</td> 
   <td>(void*) calloc (n , size in bytes)</td> 
  </tr> 
  <tr> 
   <td>Definition</td> 
   <td>It is a predefined function defined in stdlib.h header file used to allocate memory dynamically in terms of bytes.</td> 
   <td>It is predefined function present in stdlib.h header file used to allocate memory dynamically in terms of number of blocks of memory with given size in bytes.</td> 
  </tr> 
  <tr> 
   <td>No.&nbsp; of Arguments</td> 
   <td>It takes single argument.</td> 
   <td>It takes two arguments.</td> 
  </tr> 
  <tr> 
   <td>No.&nbsp; of memory blocks</td> 
   <td>Allocates a single block of memory with given byte-size.</td> 
   <td>Allocates multiple blocks of memory that are contiguous in memory with given byte-size.</td> 
  </tr> 
  <tr> 
   <td>Initialization</td> 
   <td>It does not initialize the allocated memory.</td> 
   <td>It initializes the allocated memory blocks with 0.</td> 
  </tr> 
  <tr> 
   <td>Garbage value</td> 
   <td>Present</td> 
   <td>Absent</td> 
  </tr> 
  <tr> 
   <td>Speed</td> 
   <td>It is fast.</td> 
   <td>It takes time to allocate multiple blocks of memory.</td> 
  </tr> 
  <tr> 
   <td>Used for</td> 
   <td>Creating structures</td> 
   <td>Creating dynamic Arrays</td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td> <strong>参量</strong> </td> 
   <td> <strong>malloc()</strong> </td> 
   <td> <strong>calloc()</strong> </td> 
  </tr> 
  <tr> 
   <td> 缩写为 </td> 
   <td> <strong>间</strong>存储器<strong>，alloc-</strong>分配 </td> 
   <td> <strong>C-</strong>邻接的<strong>，alloc-</strong>分配 </td> 
  </tr> 
  <tr> 
   <td> 句法： </td> 
   <td> (void *)malloc(n *字节大小) </td> 
   <td> (void *)calloc(n，大小以字节为单位) </td> 
  </tr> 
  <tr> 
   <td> 定义 </td> 
   <td> 它是stdlib.h头文件中定义的预定义函数，用于按字节动态分配内存。 </td> 
   <td> 它是stdlib.h头文件中存在的预定义函数，用于根据给定大小(以字节为单位)的内存块数动态分配内存。 </td> 
  </tr> 
  <tr> 
   <td> 参数个数 </td> 
   <td> 它需要一个参数。 </td> 
   <td> 它有两个参数。 </td> 
  </tr> 
  <tr> 
   <td> 内存块数 </td> 
   <td> 用给定的字节大小分配一个内存块。 </td> 
   <td> 以给定的字节大小分配在内存中连续的多个内存块。 </td> 
  </tr> 
  <tr> 
   <td> 初始化 </td> 
   <td> 它不会初始化分配的内存。 </td> 
   <td> 它将分配的内存块初始化为0。 </td> 
  </tr> 
  <tr> 
   <td> 垃圾价值 </td> 
   <td> 当下 </td> 
   <td> 缺席 </td> 
  </tr> 
  <tr> 
   <td> 速度 </td> 
   <td> 很快 </td> 
   <td> 分配多个内存块需要花费时间。 </td> 
  </tr> 
  <tr> 
   <td> 用于 </td> 
   <td> 建立结构 </td> 
   <td> 创建动态数组 </td> 
  </tr> 
 </tbody> 
</table>

Comment down below if you have any queries related to malloc() and calloc() in C.

如果您对C中的malloc()和calloc()有任何疑问，请在下面注释掉。

> 翻译自: [https://www.thecrazyprogrammer.com/2019/09/malloc-vs-calloc.html][https_www.thecrazyprogrammer.com_2019_09_malloc-vs-calloc.html]

calloc和malloc

[fea0e3707797622a2ae6bc36cfb5fafc.png]: /images/20221123/746fdb18d5654e958f06387bf2eec0d1.png
[dynamic memory allocation]: https://www.thecrazyprogrammer.com/2015/02/dynamic-memory-allocation-in-c.html
[void pointer]: https://www.thecrazyprogrammer.com/2015/02/void-pointer-in-c.html
[NULL pointer]: https://www.thecrazyprogrammer.com/2017/05/null-pointer-in-c.html
[https_www.thecrazyprogrammer.com_2019_09_malloc-vs-calloc.html]: https://www.thecrazyprogrammer.com/2019/09/malloc-vs-calloc.html