CGO 类型(CGO Types) 一

CGO Types

     C作为一种混合编程语言已经很久了,无论那些广泛使用的包是用何种语言实现的,都导出了和C兼容的APIGo程序调用C程序,可以借助两种工具实现,一种是cgo,另一种是SWIG工具。Cgo是为C函数创建go绑定的工具;SWIG工具可以提供更复杂的特性来调用C++程序。(关于SWIG工具的使用,可以参考以前的《calling c++ from golang with swig 》系列随笔)。

  本文主要讲述C语言类型、在CGO中可以引用的C类型及对应的引用类型名称。

  查询C99标准文档(6.2.5 Types),主要类型包括:_Boolcharsigned charunsigned charshortunsigned shortintunsigned intlongunsigned longlong longunsigned long longfloatdoublelong doublefloat _Complexdouble _Complexlong double _Complexvoid *__int128_t__uint128_t

  在CGO中引用C类型的名称可以参考CGO官方文档(Command cgo)。Go references to C 部分给出了可以引用的数值类型名称。

      综合两份参考文献,给出下面的类型列表。

C Types

Cgo  Types

_Bool

C._Bool

char

C.char

signed char

C.schar

unsigned char

C.uchar

short

C.short

unsigned short

C.ushort

int

C.int

unsigned int

C.uint

long

C.long

unsigned long

C.ulong

long long

C.longlong

unsigned long long

C.ulonglong

float

C.float

double

C.double

long double

不支持(unexpected: 16-byte float type - long double

float _Complex

C.complexfloat

double _Complex

C.complexdouble

long double _Complex

不支持( unexpected: 32-byte complex type - complex long double

void*

unsafe.Pointer

__int128_t

[16]byte

__uint128_t

[16]byte

C语言中的数值类型long doublelong double _ComplexCGO中不能引用,编译报错。

 

写一个简单的程序来演示下:

package main

/*
#include <limits.h>
#include <float.h>

_Bool b = 1;
char c = 'A';
signed char sc = CHAR_MIN;
unsigned char usc = UCHAR_MAX;
short s = SHRT_MIN;
unsigned short us = USHRT_MAX;

int i = INT_MIN;
unsigned int ui = UINT_MAX;

long l = LONG_MIN;
unsigned long ul = ULONG_MAX;

long long ll = LONG_LONG_MIN;
unsigned long long ull = ULONG_LONG_MAX;

float f = FLT_MIN;
double d = DBL_MIN;
long double ld = LDBL_MIN;

float _Complex fc = 5+5i;
double _Complex dc = 5+5i;
long double _Complex ldc = 5+5i;

__int128_t i128 = 0;
__uint128_t ui128 = 3.4028236692093846346337460743177e+38;

void *ptr = 0;

*/
import "C"
import "fmt"
import "unsafe"

func main() {
    fmt.Println(C.b)

    fmt.Println(C.c)
    fmt.Println(C.sc)
    fmt.Println(C.usc)

    fmt.Println(C.s)
    fmt.Println(C.us)

    fmt.Println(C.i)
    fmt.Println(C.ui)

    fmt.Println(C.l)
    fmt.Println(C.ul)

    fmt.Println(C.ll)
    fmt.Println(C.ull)

    fmt.Println(C.f)
    fmt.Println(C.d)
    //fmt.Println(C.ld)

    fmt.Println(C.fc)
    fmt.Println(C.dc)
    //fmt.Println(C.ldc)

    fmt.Println(C.i128)
    fmt.Println(C.ui128)

    fmt.Println(C.ptr)

    fmt.Println("-------------------------------------------------")
    fmt.Println(C._Bool(true))

    fmt.Println(C.char('A'))
    fmt.Println(C.schar(-128))
    fmt.Println(C.uchar(255))

    fmt.Println(C.short(C.SHRT_MIN))
    fmt.Println(C.ushort(C.USHRT_MAX))

    fmt.Println(C.int(C.INT_MIN))
    fmt.Println(C.uint(C.UINT_MAX))

    fmt.Println(C.long(C.LONG_MIN))
    fmt.Println(C.ulong(C.ULONG_MAX))

    fmt.Println(C.longlong(C.LONG_LONG_MIN))
    fmt.Println(C.ulonglong(18446744073709551615))

    fmt.Println(C.float(-1))
    fmt.Println(C.double(-1))
    //fmt.Println(C.longdouble(1))

    fmt.Println(C.complexfloat(5 + 5i))
    fmt.Println(C.complexdouble(5 + 5i))

    C.i128 = [16]byte{15: 127}
    fmt.Println(C.i128)

    C.ui128 = [16]byte{15: 255}
    fmt.Println(C.ui128)

    C.ptr = unsafe.Pointer(nil)
    fmt.Println(C.ptr)

}

  

运行后,输出结果如下:(运行环境:Windows 7 64位操作系统,go version go1.8.3 windows/amd64

 

true
65
-128
255
-32768
65535
-2147483648
4294967295
-2147483648
4294967295
-9223372036854775808
18446744073709551615
1.1754944e-38
2.2250738585072014e-308
(5+5i)
(5+5i)
[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
[255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255]
<nil>
-------------------------------------------------
true
65
-128
255
-32768
65535
-2147483648
4294967295
-2147483648
4294967295
-9223372036854775808
18446744073709551615
-1
-1
(5+5i)
(5+5i)
[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 127]
[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 255]
<nil>

 

posted @ 2017-10-11 13:10 majianguo 阅读(...) 评论(...) 编辑 收藏