cgo example

go/goutil/cgo/hello.c

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+# include "hello.h" 
+
+void hello(char *s){
+  printf("hello cgo! \n %s",s);
+}

go/goutil/cgo/hello.h

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+# include <stdio.h> 
+
+void hello( char *s);

go/goutil/cgo/readme.md

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+# cgo
+
+- 编译c函数为动态链接库  
+
+```
+# include <stdio.h> 
+void hello( char *s);
+```
+
+```c
+# include "hello.h" 
+void hello(char *s){
+  printf("hello cgo! \n %s",s);
+}
+```
+
+- 编译成 动态链接库
+
+  ```
+  gcc -shared -fPIC -o libhello.dll hello.c
+  ```
+
+
+- 编写 go main函数
+
+  ```go
+  // test_hello.go 
+  package main 
+  /*
+  #cgo LDFLAGS: -L. -lhello 
+  #include<stdio.h>
+  #include<stdlib.h>
+  #include"hello.h"
+  */
+  import "C"
+  import (
+  	"unsafe"
+  )
+  
+  func main(){
+  	s:=" hello\n";
+  	cs:=C.CString(s);
+  	C.hello(cs);
+  	defer C.free(unsafe.Pointer(cs));
+  
+  
+  }
+  ```
+
+- 运行  
+
+  ```
+  go run test_hello.go 
+  ```
+
+- https://golang.org/cmd/cgo/#hdr-C_references_to_Go
+
+
+

go/goutil/cgo/test_hello.go

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+package main 
+
+/*
+#cgo LDFLAGS: -L. -lhello 
+#include<stdio.h>
+#include<stdlib.h>
+#include"hello.h"
+*/
+import "C"
+import (
+	"unsafe"
+)
+
+func main(){
+	s:=" hello\n";
+	cs:=C.CString(s);
+	C.hello(cs);
+	defer C.free(unsafe.Pointer(cs));
+
+
+}