openNextFile()
描述
開啟下一個檔案或是資料夾。
語法
file.openNextFile()
參數
file
:被 SD.open()
回傳的 File
物件
回傳
File
:如果檔案開啟成功回傳一個指向該檔案的 File
物件,如果開啟失敗則該 File
物件在使用 if
判斷時與布林值的 false
相等
範例
#include <SD.h> File root; void setup() { Serial.begin(9600); SD.begin(); root = SD.open("/"); printDirectory(root, 0); Serial.println("done!"); } void loop() { // 不做任何事 } void printDirectory(File dir, int numTabs) { while(true) { File entry = dir.openNextFile(); if (! entry) { // 沒有未被開啟的檔案了 Serial.println("**no more files**"); } for (uint8_t i=0; i<numTabs; i++) { Serial.print('\t'); } Serial.print(entry.name()); if (entry.isDirectory()) { Serial.println("/"); printDirectory(entry, numTabs+1); } else { // 如果是檔案會印出檔案大小 Serial.print("\t\t"); Serial.println(entry.size(), DEC); } entry.close(); } }
See Also
- isDirectory()
- rewindDirectory()
The text of the 86Duino reference is a modification of the Arduino reference, and is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.