摘要

指针是C语言中的一种数据类型，总结:总结：
指针类型的变量宽度永远是4字节、无论类型是什么 无论有几个*。

C语言14 指针类型

指针是C语言中的一种数据类型，

定义带 "*"类型的变量

char    x;          char*       x; short   y;          short*      y; int     z;          int*        z; float   f;          float*      f; double  d;          double*     d; Student st;         Student*    st;

总结:

1. 任何带有*的变量类型的标准写法：变量类型* 变量名
2. 任何类型都可以带* 加上* 以后是新的类型，统称为“指针类型”
3. *可以使任意多个。

指针变量赋值

char* x;        char*** x;          char******* x; short* ~~ int* ~~ Student* ~~ x = (char*)1; y = (short*)2;  int******* x; int******* y; x = (int*******)4; y = x;  char x; x = 1;

指针变量的宽度

char x;     char* x;        char******** x; short y;    short* y;       short******** y; ~~  x=1;    x=(char*)1;         x=(char********)1; ~~     9:        char* x; 10:       short* y; 11:       int* z; 12: 13:       x = (char*)1; 00401028 C7 45 FC 01 00 00 00 mov         dword ptr [ebp-4],1 14:       y=(short*)2; 0040102F C7 45 F8 02 00 00 00 mov         dword ptr [ebp-8],2 15:       z=(int*)3; 00401036 C7 45 F4 03 00 00 00 mov         dword ptr [ebp-0Ch],3   9:        char******** x; 10:       short******** y; 11:       int******** z; 12: 13:       x = (char********)1; 00401028 C7 45 FC 01 00 00 00 mov         dword ptr [ebp-4],1 14:       y=(short********)2; 0040102F C7 45 F8 02 00 00 00 mov         dword ptr [ebp-8],2 15:       z=(int********)3; 00401036 C7 45 F4 03 00 00 00 mov         dword ptr [ebp-0Ch],3

总结：
指针类型的变量宽度永远是4字节、无论类型是什么 无论有几个*。

指针类型自加和自减(++ / --)

char a;                     char**** a; short b;                    short**** b; int c;                      int**** c; a=100;                      a=(char****)100; b=100;                      b=(short****)100; c=100;                      c=(int****)100; a++;                        a++; b++;                        b++; c++;                        c++;  printf("%d %d %d",a,b,c);   printf("%d %d %d",a,b,c);  11:       char* a; 12:       short* b; 13:       int* c; 14:       a=(char*)100; 0040B488 C7 45 FC 64 00 00 00 mov         dword ptr [ebp-4],64h 15:       b=(short*)100; 0040B48F C7 45 F8 64 00 00 00 mov         dword ptr [ebp-8],64h 16:       c=(int*)100; 0040B496 C7 45 F4 64 00 00 00 mov         dword ptr [ebp-0Ch],64h 17:       a++; 0040B49D 8B 45 FC             mov         eax,dword ptr [ebp-4] 0040B4A0 83 C0 01             add         eax,1 0040B4A3 89 45 FC             mov         dword ptr [ebp-4],eax 18:       b++; 0040B4A6 8B 4D F8             mov         ecx,dword ptr [ebp-8] 0040B4A9 83 C1 02             add         ecx,2 0040B4AC 89 4D F8             mov         dword ptr [ebp-8],ecx 19:       c++; 0040B4AF 8B 55 F4             mov         edx,dword ptr [ebp-0Ch] 0040B4B2 83 C2 04             add         edx,4 0040B4B5 89 55 F4             mov         dword ptr [ebp-0Ch],edx  比如  int* c =1; c++; 去掉* 是int   4个字节 就+4; char* c=1; c++; 去掉* 是char  1个字节 就+1 char** c=1; c++; 去掉* 是char* 指针类型是4个字节 就+4   指针类型变量+N=指针类型变量+N*(去掉一个*后类型的宽度) 指针类型变量-N=指针类型变量-N*(去掉一个*后类型的宽度) 

总结、

1. 不带*变量的变量，++或者--都是加1 或者减1
2. 带*类型的变量m,++或者-- 新增（减少）的数量是去掉一个*后变量的宽度

指针类型的比较

char**** a; char**** b; a = (char****)200; b = (char****)100; if(a>b) {     printf("1"); } else {     printf("2"); }  12:       char**** a; 13:       char**** b; 14:       a = (char****)200; 0040B488 C7 45 FC C8 00 00 00 mov         dword ptr [ebp-4],0C8h 15:       b = (char****)100; 0040B48F C7 45 F8 64 00 00 00 mov         dword ptr [ebp-8],64h 16:       if(a>b) 0040B496 8B 45 FC             mov         eax,dword ptr [ebp-4] 0040B499 3B 45 F8             cmp         eax,dword ptr [ebp-8] 0040B49C 76 0F                jbe         main+3Dh (0040b4ad) 17:       { 18:           printf("1"); 0040B49E 68 1C F0 41 00       push        offset string "1" (0041f01c) 0040B4A3 E8 A8 02 00 00       call        printf (0040b750) 0040B4A8 83 C4 04             add         esp,4 19:       } 20:       else 0040B4AB EB 0D                jmp         main+4Ah (0040b4ba) 21:       { 22:           printf("2"); 0040B4AD 68 50 FE 41 00       push        offset string "2" (0041fe50) 0040B4B2 E8 99 02 00 00       call        printf (0040b750) 0040B4B7 83 C4 04             add         esp,4  //这里编译器使用了jbe指令 jbe指令是用来比较无符号数的，也就说明指针类型是无符号数

总结
指针类型可以做大小比较