openNextFile()
描述
开启下一个档案或是资料夹。
语法
file.openNextFile()
参数
file
:被 SD.open()
回传的 File
物件
回传
File
:如果档案开启成功回传一个指向该档案的 File
物件,如果开启失败则该 File
物件在使用 if
判断时与布林值的 false
相等
范例
#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) { // 没有未被开启的档案了 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 { // 如果是档案会印出档案大小 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.