go - io.Copy() erase the Reader content - 


  पैकेज मुख्य आयात ("fmt" "io" "io / ioutil" "os") func मुख्य () {File, err: = os.Open ("HelloWorld") अगर शून्य! = गलती {fmt.Println (err)} defer file.Close () fileTo, err: = os.Create ("fileTo") अगर शून्य! = त्रुटि {fmt.Println (err)} defer file.Close () _, err = io.Copy (fileTo, file) अगर शून्य! = Err {fmt.Println (err)} fileByteOne, err: = ioutil.ReadAll (फ़ाइल) ) अगर शून्य! = गलती {fmt.Println (err)} fmt.Println (fileByteOne)}   
 io.Copy () फ़ाइल सामग्री को मिटा देगा, आउटपुट है:  
  []   
 प्रतिलिपि (डीएसटी लेखक, स्रोत रीडर) प्रतिलिपि स्रोत से डीएसटी, यह src सामग्री मिटा देगा क्या मिटा देने से बचने का कोई तरीका है?   
 
 
 
  io.Copy (फ़ाइल, फाइल )  फ़ाइल सामग्री मिटा देगा   
 यह नहीं होगा लेकिन यह पढ़ने की स्थिति को  EOF  पर ले जाएगा, जिसका अर्थ है अगले  ioutil.ReadAll ()  से शुरू होगा ...  EOF ।  
 आप इसे बंद कर सकते हैं और अपने  ioutil.ReadAll ()  से पहले ' फ़ाइल ' पुनः खोल सकते हैं। वैसे, आपके पास दो  defer file.Close ()  उदाहरण: दूसरा वाला होना चाहिए  defer fileTo.Close () । या, सरल, एक के साथ इसे रीसेट करें, जैसा कि सुझाव दिया गया है एस।  
  _, err = file.Seek (0, os.SEEK_SET)   
 यह है इसमें भी सचित्र है:  
 
 कोई अंतर्निहित रिवाइंड नहीं है, लेकिन  ढूंढें (0, 0)  इसे पूरा करता है।   
 ( os.SEEK_SET  परिभाषित है, जैसा कि  0 )  
  const SEEK_SET int = 0 // फ़ाइल की उत्पत्ति के सापेक्ष खोजना

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