背景：

　　这片文章主要是记录以前的误区，以前C/C++这块还是大学中学习的一点知识，好久不用，基本都忘记啦。一直误以为数组的大小和指针的大小一样，最近通过学习learn c the hard way发现并不是这样。这个其实没有太多可说的，直接上demo。

demo代码:

1 #include 
     
       2  3 int main(int argc, char *argv[]) 4 { 5     int areas[] = {
   10, 12, 13, 14, 20}; 6     char name[] = "Zhaosc"; 7     char full_name[] = { 8         'Z', 'h', 'a', 'o', 9         ' ', 'S', 'h', 'u', ' ',10         'c', 'h', 'a', 'o', '\0'11     };12     13     int a = 10;14     int *a_ptr = &a;15     char c = 'b';16     char *c_ptr = &c;17 18     printf("the size of the variable int pointer is %ld.\n", sizeof(a_ptr));19     printf("the size of the variable char pointer is %ld.\n", sizeof(c_ptr));20 21     // WARNING: On some systems you may have to change the22     // %ld in this code to a %u since it will use unsigned ints23     printf("The size of an int: %ld\n", sizeof(int));24     printf("The size of areas (int[]): %ld\n",25            sizeof(areas));26     printf("The number of ints in areas: %ld\n",27            sizeof(areas) / sizeof(int));28     printf("The first area is %d, the 2nd %d.\n",29            areas[0], areas[1]);30     31     printf("The size of a char: %ld\n", sizeof(char));32     printf("The size of name (char[]): %ld\n",33            sizeof(name));34     printf("The number of chars: %ld\n",35            sizeof(name) / sizeof(char));36     37     printf("The size of full_name (char[]): %ld\n",38            sizeof(full_name));39     printf("The number of chars: %ld\n",40            sizeof(full_name) / sizeof(char));41     42     printf("name=\"%s\" and full_name=\"%s\"\n",43            name, full_name);44     45     return 0;46 }
     

运行结果：

zhaoscmatoMacBook-Pro:c zhaosc$ ./ex8the size of the variable int pointer is 8.the size of the variable char pointer is 8.The size of an int: 4The size of areas (int[]): 20The number of ints in areas: 5The first area is 10, the 2nd 12.The size of a char: 1The size of name (char[]): 7The number of chars: 7The size of full_name (char[]): 14The number of chars: 14name="Zhaosc" and full_name="Zhao Shu chao"

分析：

根据输出一行一行分析

1.int和char的指针在内存的大小都是8个字节，指针在内存中的大小和指针类型没有区别，例如函数指针也是一样的。

2.int在内存占用4个字节，这个是不确定的，和具体的操作系统位数有关系。

3.int数组在内存中占用20个字节，正好是4*5.areas中有5个整数。

4.char在内存中占用1个字节，这个是确定的。

5.char数组占用内存是7个字节，同样为1*7.

Note：如博文中存在问题，请大家及时指出，我会及时纠正，谢谢。