我在arduino IDE上使用LittleFS库和ESP32。 我正在使用LittleFS的示例readFile函数读取文件,但正在尝试根据需要对其进行转换。 写入文件的文本具有以下形式: LettersAndNumbersMax30&LettersAndNumbersMax30&00&00&01&01
由&分隔。 2个文本值,最多30个字符和4个整数。
我要构建: char * mytest1包含第一个文本 char * mytest2包含第二个文本 包含第一个整数(2个数字)的int mytest3 int mytest4包含第二个整数(2个数字) int mytest5包含第三个整数(2个数字) int mytest5包含第四个整数(2个数字)
file.read()总是返回整数。例如&的38。
void readFile(fs::FS &fs, const char * path){
Serial.printf("Reading file: %s\r\n", path);
File file = fs.open(path);
if(!file || file.isDirectory()){
Serial.println("- failed to open file for reading");
return;
}
Serial.println("- read from file:");
while(file.available()){
Serial.write(file.read());
}
file.close();
}
答案 0 :(得分:0)
file.read返回整数。这样就打印出了整数。
您将其转换为字符串。
while(file.available()){
char s[2] = {0};
s[0] = file.read();
Serial.write(s);
}
答案 1 :(得分:0)
它相当简单。测试每个读取的字节并采取相应措施。下面的代码不处理符号或负数。它还不会检查文件中是否只有整数数字。
#include ....
struct record_t
{
char myState1[31];
char myState2[31];
int myState3;
int myState4;
int myState5;
int myState6;
};
record_t record;
bool readFile(fs::FS &fs, const char * path);
void setup()
{
// ...
}
void loop()
{
//...
if (readFile(/*...*/))
{
Serial.printf("file reads OK\r\n");
//...
}
}
bool readFile(fs::FS &fs, const char * path)
{
Serial.printf("Reading file: %s\r\n", path);
File file = fs.open(path);
if (!file || file.isDirectory())
{
Serial.println("- failed to open file for reading");
return;
}
Serial.println("- read from file:");
int state = 0;
int index = 0;
// clear record.
record.myState1[0] = 0;
record.myState2[0] = 0;
record.myState3 = 0;
record.myState4 = 0;
record.myState5 = 0;
record.myState6 = 0;
bool valid = false;
for (int i = file.read(); i != -1; i = file.read())
{
char c = i & 0xFF;
Serial.write(c); // file.read() returns an int, that's why Serial.write()
// was printing numbers.
switch(state)
{
case 0:
if (index > sizeof(record.myState1) - 1) // avoid buffer overflow
index = sizeof(record.myState1) - 1;
if (c != '&')
{
record.myState1[index++] = c;
}
else
{
record.myState1[index] = 0;
++state;
index = 0;
}
break;
case 1:
if (index > sizeof(record.myState2) - 1) // avoid buffer overflow
index = sizeof(record.myState2) - 1;
if (c != '&')
{
record.myState2[index++] = c;
}
else
{
record.myState2[index] = 0;
++state;
index = 0;
}
break;
case 2:
if (c != '&')
record.myState3 = record.myState3 * 10 + (c - '0');
else
++state;
break;
case 3:
if (c != '&')
record.myState4 = record.myState4 * 10 + (c - '0');
else
++state;
break;
case 4:
if (c != '&')
record.myState5 = record.myState5 * 10 + (c - '0');
else
++state;
break;
case 5:
valid = true;
if (c != '&')
record.myState6 = record.myState6 * 10 + (c - '0');
else
++state;
break;
default: // reaching here is an error condition? You decide.
return false;
}
}
file.close();
if (!valid)
{
// clear record.
record.myState1[0] = 0;
record.myState2[0] = 0;
record.myState3 = 0;
record.myState4 = 0;
record.myState5 = 0;
record.myState6 = 0;
}
return valid;
}