doudao7113
2016-08-31 13:30 阅读 57
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无法在Golang应用程序中使用通过cgo编译的C库?

I am trying to wrap a C library in Golang. I am trying to call a C function in an already compiled library. I have both a .a file and a .so library file.

Where do I need to place the library files and how do i tell cgo that I am using these libraries?

I am rather a novice when it comes to C. Any help would be greatly appreciated.

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1条回答 默认 最新

  • 已采纳
    dongyuntao2000 dongyuntao2000 2016-08-31 15:15

    I'll explain it with this sample:

    First build libhello.a using ./libs/m.c:

    #include <stdint.h> 
    
    extern uint64_t Add(uint64_t a, uint64_t b) {
        return a + b;
    }
    

    For this test sample libhello.a is inside ./libs/ :

    m.go
    └───libs
        m.c
        libhello.a
    

    Then go build this m.go working sample:

    package main
    
    //#cgo LDFLAGS: -L${SRCDIR}/libs -lhello
    //#include <stdint.h>
    //extern uint64_t Add(uint64_t a, uint64_t b);
    import "C"
    
    import (
        "fmt"
    )
    
    func main() {
        fmt.Println(C.Add(C.uint64_t(10), C.uint64_t(20))) // 30
    }
    

    output:

    30
    

    When the cgo directives are parsed, any occurrence of the string ${SRCDIR} will be replaced by the absolute path to the directory containing the source file. This allows pre-compiled static libraries to be included in the package directory and linked properly. For example if package foo is in the directory /go/src/foo:

    // #cgo LDFLAGS: -L${SRCDIR}/libs -lfoo
    

    Will be expanded to:

    // #cgo LDFLAGS: -L/go/src/foo/libs -lfoo
    
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