数组内存中分布情况

0. 二维数组
   注意栈中地址是从高地址向低地址生长：

(gdb) p/x &arr[0][0]
$7 = 0x7fffffffe440
(gdb) p/x &arr[0][1]
$8 = 0x7fffffffe444
(gdb) p/x &arr[0][2]
$9 = 0x7fffffffe448
(gdb) p/x &arr[0][3]
$10 = 0x7fffffffe44c

(gdb) p/x &arr[1][0]
$11 = 0x7fffffffe450
(gdb) p/x &arr[1][1]
$12 = 0x7fffffffe454
(gdb) p/x &arr[1][2]
$13 = 0x7fffffffe458
(gdb) p/x &arr[1][3]
$14 = 0x7fffffffe45c

(gdb) p/x &arr[2][0]
$15 = 0x7fffffffe460
(gdb) p/x &arr[2][1]
$16 = 0x7fffffffe464
(gdb) p/x &arr[2][2]
$17 = 0x7fffffffe468
(gdb) p/x &arr[2][3]
$18 = 0x7fffffffe46c

(gdb) p/x &arr[3][0]
$19 = 0x7fffffffe470
(gdb) p/x &arr[3][1]
$20 = 0x7fffffffe474
(gdb) p/x &arr[3][2]
$21 = 0x7fffffffe478
(gdb) p/x &arr[3][3]
$22 = 0x7fffffffe47c

即如下图走向：

         0     1     2    3  
    0  ------------------->  
    1  ------------------->  
    2  ------------------->  
    3  ------------------->  

0. 一维数组在内存中的分布情况：

(gdb) p/x &a[0]                             
$1 = 0x7fffffffe460
(gdb) p/x &a[1]
$2 = 0x7fffffffe464
(gdb) p/x &a[2]
$3 = 0x7fffffffe468
(gdb) p/x &a[3]
$4 = 0x7fffffffe46c
(gdb) p/x &a[4]
$5 = 0x7fffffffe470
(gdb) p/x &a[5]
$6 = 0x7fffffffe474

低地址            高地址
a  0    1    2    3     4
    --------------------->

0. c中栈是由高地址向低地址延伸,堆则是从低地址想高地址延伸

  栈底
___________
|     a[5]     |     高地址
|     a[4]     |
|     a[3]     |
|     a[2]     |
|     a[1]     |
|     a[0]     |      低地址 
      栈顶

0. C程序内存中的组织形式

    【代码区    】  高地址
    【静态数据区 】
    【栈        】
     -----------
     -----------
     -----------
     -----------
    【 堆       】 低地址