Created
February 7, 2017 23:24
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cgo
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// A simple cgo example for writing to a file. | |
package main | |
// #include <stdlib.h> | |
// #include <stdio.h> | |
import "C" | |
import ( | |
"errors" | |
"fmt" | |
"unsafe" | |
) | |
// FileReadWrite means we can read and/or write to the file. | |
const FileReadWrite = "w+" | |
// ErrWrite indicates a write did not complete successfully. | |
var ErrWrite = errors.New("failed to write") | |
// File is any file in the file system. | |
type File struct { | |
fp *C.FILE | |
name string | |
} | |
// Open returns a new File for writing. | |
func Open(filename string) (*File, error) { | |
cFilename := C.CString(filename) | |
cMode := C.CString(FileReadWrite) | |
defer C.free(unsafe.Pointer(cFilename)) | |
defer C.free(unsafe.Pointer(cMode)) | |
fp, err := C.fopen(cFilename, cMode) | |
if err != nil { | |
return nil, err | |
} | |
return &File{ | |
fp: fp, | |
name: filename, | |
}, nil | |
} | |
// Close frees up the File's memory and closes the file descriptor. | |
func (f *File) Close() { | |
C.fclose(f.fp) | |
} | |
// Write prints a string into the file. | |
func (f *File) Write(content string) error { | |
size := C.size_t(len(content)) | |
cContent := unsafe.Pointer(C.CString(content)) | |
defer C.free(cContent) | |
n := C.fwrite(cContent, size, 1, f.fp) | |
if n == 0 { | |
return ErrWrite | |
} | |
return nil | |
} | |
func main() { | |
f, err := Open("tmp.txt") | |
if err != nil { | |
fmt.Printf("failed to open file: %s", err) | |
} | |
defer f.Close() | |
f.Write("hello\n") | |
} |
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