如何将Go字符串数组转换为C字符串数组？

huangapple
go评论124阅读模式
英文:

How do I convert a Go array of strings to a C array of strings?

问题

我正在一个项目中使用cgo，并且想要导出一个函数供使用。以下是我想要实现的示例代码：

  1. package csplit
  3. import (
  4.     "C"
  5.     "strings"
  6. )
  8. //export Split
  9. /* Split函数接受两个C字符串作为参数，第二个字符串表示要进行分割的子字符串，然后返回一个字符串数组。示例：
  10.    Split("1,2", ",") // 返回["1", "2"]
  11. */
  12. func Split(original *C.char, split *C.char) []*C.char {
  13.     goResult := strings.Split(C.GoString(original), C.GoString(split))
  14.     cResult := make([]*C.char, len(goResult))
  16.     for idx, substring := range goResult {
  17.         cResult[idx] = C.CString(substring)
  18.     }
  20.     return cResult
  21. }

问题在于返回类型是Go分配的数据，而不是移动到C堆上。这会导致出现以下错误：runtime error: cgo result has Go pointer。

英文:

I am using cgo in a project, and I want to export a function for use. Here's an example of what I want to achieve:

  1. package csplit
  3. import (
  4.     "C"
  5.     "strings"
  6. )
  8. //export Split
  9. /* The Split function takes two C strings, the second of which represents
  10.    a substring to split on, and returns an array of strings. Example:
  11.        Split("1,2", ",") // gives ["1", "2"]
  12. */
  13. func Split(original *C.char, split *C.char) []*C.char {
  14.         goResult := strings.Split(C.GoString(original), C.GoString(split))
  15.         cResult := make([]*C.char, len(goResult))
  17.         for idx, substring := range goResult {
  18.                 cResult[idx] = C.CString(substring)
  19.         }
  21.         return cResult
  22. }

The problem is that the return type is Go allocated data, and not moved into the C heap. This panics with: runtime error: cgo result has Go pointer

答案1

得分: 14

你正在返回一个在Go中分配的Go切片，它与C数组是不同的结构。你需要在C中分配一个数组：

  1. //export Split
  2. func Split(original *C.char, split *C.char) **C.char {
  3.     goResult := strings.Split(C.GoString(original), C.GoString(split))
  4.     cArray := C.malloc(C.size_t(len(goResult)) * C.size_t(unsafe.Sizeof(uintptr(0))))
  6.     // 将C数组转换为Go数组，以便我们可以对其进行索引
  7.     a := (*[1<<30 - 1]*C.char)(cArray)
  9.     for idx, substring := range goResult {
  10.         a[idx] = C.CString(substring)
  11.     }
  13.     return (**C.char)(cArray)
  14. }
英文:

You're returning a Go slice which is allocated in Go, and is a different structure than a C array. You need to allocate an array in C:

  1. //export Split
  2. func Split(original *C.char, split *C.char) **C.char {
  3. 	goResult := strings.Split(C.GoString(original), C.GoString(split))
  4. 	cArray := C.malloc(C.size_t(len(goResult)) * C.size_t(unsafe.Sizeof(uintptr(0))))
  6. 	// convert the C array to a Go Array so we can index it
  7. 	a := (*[1&lt;&lt;30 - 1]*C.char)(cArray)
  9. 	for idx, substring := range goResult {
  10. 		a[idx] = C.CString(substring)
  11. 	}
  13. 	return (**C.char)(cArray)
  14. }

huangapple
  • 本文由 发表于 2017年1月6日 02:24:35
  • 转载请务必保留本文链接：https://go.coder-hub.com/41492071.html
  • arrays
  • c
  • cgo
  • go
  • string
匿名

发表评论

匿名网友

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen:

确定