为什么不能这样呢？

[WJN92]

#define kb 1024
tL1[ 4* kb / sizeof( L2 ) ];

里面L2,kb已经定义了，当时编译报错，为什么呢？

[WJN92]

引用 4 楼 VisualEleven 的回复:

[quote=引用 楼主 WJN92 的回复:] #define kb 1024 tL1[ 4* kb / sizeof( L2 ) ]; 里面L2,kb已经定义了，当时编译报错，为什么呢？

你这个是定义数组吗？类型呢？[/quote] 有的，我忘记复制而已 #define def_NumDetectUnitLineTableSize (4 * kb / sizeof(FE_DetectUnitL1)) struct FE_DetectUnitLT { DWORD dwPointer; FE_DetectUnitL1 tL1DetectUnit[def_NumDetectUnitLineTableSize];

[WJN92]

引用 5 楼 zhao4zhong1 的回复:

VC编译选项加/EP /P，重新编译，查看宏展开后对应的.i文件。gcc加-E http://bbs.csdn.net/topics/391003898

应该怎样设置呢？ 我用的是vs2015, 设置的项目叫什么名字呢？ 谢谢老师

[WJN92]

引用 5 楼 zhao4zhong1 的回复:

VC编译选项加/EP /P，重新编译，查看宏展开后对应的.i文件。gcc加-E http://bbs.csdn.net/topics/391003898

设置过了，好像也不行呢 Error:incomplete type is not allowed

[赵4老师]

引用 8 楼 WJN92 的回复:

[quote=引用 5 楼 zhao4zhong1 的回复:] VC编译选项加/EP /P，重新编译，查看宏展开后对应的.i文件。gcc加-E http://bbs.csdn.net/topics/391003898

设置过了，好像也不行呢 Error:incomplete type is not allowed[/quote] 前提是能编译通过。 项目、属性、配置属性、C/C++、预处理器、预处理到文件：是，预处理取消显示行号：是

[schlafenhamster]

Incomplete Types An incomplete type is a type that describes an identifier but lacks information needed to determine the size of the identifier. An “incomplete type” can be: A structure type whose members you have not yet specified. A union type whose members you have not yet specified. An array type whose dimension you have not yet specified. The void type is an incomplete type that cannot be completed. To complete an incomplete type, specify the missing information. The following examples show how to create and complete the incomplete types. To create an incomplete structure type, declare a structure type without specifying its members. In this example, the ps pointer points to an incomplete structure type called student. struct student *ps; To complete an incomplete structure type, declare the same structure type later in the same scope with its members specified, as in struct student { int num; } /* student structure now completed */ To create an incomplete array type, declare an array type without specifying its repetition count. For example: char a[]; /* a has incomplete type */ To complete an incomplete array type, declare the same name later in the same scope with its repetition count specified, as in char a[25]; /* a now has complete type */ 注意 def_NumDetectUnitLineTableSize 必须 有 值

[WJN92]

引用 10 楼 schlafenhamster 的回复:

Incomplete Types An incomplete type is a type that describes an identifier but lacks information needed to determine the size of the identifier. An “incomplete type” can be: A structure type whose members you have not yet specified. A union type whose members you have not yet specified. An array type whose dimension you have not yet specified. The void type is an incomplete type that cannot be completed. To complete an incomplete type, specify the missing information. The following examples show how to create and complete the incomplete types. To create an incomplete structure type, declare a structure type without specifying its members. In this example, the ps pointer points to an incomplete structure type called student. struct student *ps; To complete an incomplete structure type, declare the same structure type later in the same scope with its members specified, as in struct student { int num; } /* student structure now completed */ To create an incomplete array type, declare an array type without specifying its repetition count. For example: char a[]; /* a has incomplete type */ To complete an incomplete array type, declare the same name later in the same scope with its repetition count specified, as in char a[25]; /* a now has complete type */ 注意 def_NumDetectUnitLineTableSize 必须 有 值

我想让编译器帮我计算而已

[赵4老师]

宏是一种语法糖。 语法糖越甜，编译调试查错越苦！ 把有限的生命浪费在品尝/品鉴无穷多种的语法糖中，我认为不值当。

[zhusg]

你这语句是对tL1赋值还是取值呢？

[WJN92]

引用 12 楼 zhao4zhong1 的回复:

宏是一种语法糖。 语法糖越甜，编译调试查错越苦！ 把有限的生命浪费在品尝/品鉴无穷多种的语法糖中，我认为不值当。

但是我这样灵活啊，好像在编译64位 和 32位的代码时候 因为希望能存优化对齐，所以才使用宏来计算，否则的话，我要把所有的定义都要改一遍，还不知道有没有遗落

[赵4老师]

对齐请使用 #pragma pack(16)

#include <stdio.h>
#define field_offset(s,f) (int)(&(((struct s *)(0))->f))
struct AD  { int a; char b[13]; double c;};
#pragma pack(push)
#pragma pack(1)
struct A1  { int a; char b[13]; double c;};
#pragma pack(2)
struct A2  { int a; char b[13]; double c;};
#pragma pack(4)
struct A4  { int a; char b[13]; double c;};
#pragma pack(8)
struct A8  { int a; char b[13]; double c;};
#pragma pack(16)
struct A16 { int a; char b[13]; double c;};
#pragma pack(pop)
int main() {
    printf("AD.a %d\n",field_offset(AD,a));
    printf("AD.b %d\n",field_offset(AD,b));
    printf("AD.c %d\n",field_offset(AD,c));
    printf("\n");
    printf("A1.a %d\n",field_offset(A1,a));
    printf("A1.b %d\n",field_offset(A1,b));
    printf("A1.c %d\n",field_offset(A1,c));
    printf("\n");
    printf("A2.a %d\n",field_offset(A2,a));
    printf("A2.b %d\n",field_offset(A2,b));
    printf("A2.c %d\n",field_offset(A2,c));
    printf("\n");
    printf("A4.a %d\n",field_offset(A4,a));
    printf("A4.b %d\n",field_offset(A4,b));
    printf("A4.c %d\n",field_offset(A4,c));
    printf("\n");
    printf("A8.a %d\n",field_offset(A8,a));
    printf("A8.b %d\n",field_offset(A8,b));
    printf("A8.c %d\n",field_offset(A8,c));
    printf("\n");
    printf("A16.a %d\n",field_offset(A16,a));
    printf("A16.b %d\n",field_offset(A16,b));
    printf("A16.c %d\n",field_offset(A16,c));
    printf("\n");
    return 0;
}
//AD.a 0
//AD.b 4
//AD.c 24
//
//A1.a 0
//A1.b 4
//A1.c 17
//
//A2.a 0
//A2.b 4
//A2.c 18
//
//A4.a 0
//A4.b 4
//A4.c 20
//
//A8.a 0
//A8.b 4
//A8.c 24
//
//A16.a 0
//A16.b 4
//A16.c 24
//
//

[schlafenhamster]

根据 32 位 64位 定义 #def 32位 #define def_NumDetectUnitLineTableSize xxxx #else #define def_NumDetectUnitLineTableSize yyyy #endif

[schlafenhamster]

#define kb 1024 #define tL1 int // type of L1 #define tL2 int // type of L2 tL1 L1[4* kb / sizeof(tL2)]={0};

[worldy]

tL1[ 4* kb / sizeof( L2 ) ]; 这个算是什么？定义数组？数据类型呢？

[WJN92]

引用 14 楼 zhao4zhong1 的回复:

对齐请使用 #pragma pack(16)

#include <stdio.h>
#define field_offset(s,f) (int)(&(((struct s *)(0))->f))
struct AD  { int a; char b[13]; double c;};
#pragma pack(push)
#pragma pack(1)
struct A1  { int a; char b[13]; double c;};
#pragma pack(2)
struct A2  { int a; char b[13]; double c;};
#pragma pack(4)
struct A4  { int a; char b[13]; double c;};
#pragma pack(8)
struct A8  { int a; char b[13]; double c;};
#pragma pack(16)
struct A16 { int a; char b[13]; double c;};
#pragma pack(pop)
int main() {
    printf("AD.a %d\n",field_offset(AD,a));
    printf("AD.b %d\n",field_offset(AD,b));
    printf("AD.c %d\n",field_offset(AD,c));
    printf("\n");
    printf("A1.a %d\n",field_offset(A1,a));
    printf("A1.b %d\n",field_offset(A1,b));
    printf("A1.c %d\n",field_offset(A1,c));
    printf("\n");
    printf("A2.a %d\n",field_offset(A2,a));
    printf("A2.b %d\n",field_offset(A2,b));
    printf("A2.c %d\n",field_offset(A2,c));
    printf("\n");
    printf("A4.a %d\n",field_offset(A4,a));
    printf("A4.b %d\n",field_offset(A4,b));
    printf("A4.c %d\n",field_offset(A4,c));
    printf("\n");
    printf("A8.a %d\n",field_offset(A8,a));
    printf("A8.b %d\n",field_offset(A8,b));
    printf("A8.c %d\n",field_offset(A8,c));
    printf("\n");
    printf("A16.a %d\n",field_offset(A16,a));
    printf("A16.b %d\n",field_offset(A16,b));
    printf("A16.c %d\n",field_offset(A16,c));
    printf("\n");
    return 0;
}
//AD.a 0
//AD.b 4
//AD.c 24
//
//A1.a 0
//A1.b 4
//A1.c 17
//
//A2.a 0
//A2.b 4
//A2.c 18
//
//A4.a 0
//A4.b 4
//A4.c 20
//
//A8.a 0
//A8.b 4
//A8.c 24
//
//A16.a 0
//A16.b 4
//A16.c 24
//
//

如果要计算4K一页呢？链表

[Eleven]

引用 楼主 WJN92 的回复:

#define kb 1024 tL1[ 4* kb / sizeof( L2 ) ]; 里面L2,kb已经定义了，当时编译报错，为什么呢？

你这个是定义数组吗？类型呢？

[赵4老师]

VC编译选项加/EP /P，重新编译，查看宏展开后对应的.i文件。gcc加-E http://bbs.csdn.net/topics/391003898