Fstream does not work

Projects Programming
1

Hi Guys,

I am new to this set-up and started to have problems while compiling the program. This is the snapshot of my code:

#include <fstream>

void setup() {
  std::fstream file;
  file.open("abc.txt", std::ios::out | std::fstream::app);                                           
  if(!file.is_open()) {
    Serial.println("ERROR1: FILE NOT OPENED.");                                                      
  }     
}

There is nothing inside loop function. it is empty.

Problem is that for some reason, I see this message:

ERROR1: FILE NOT OPENED.

I would like to understand why. There are no issues during the compilation as well. I would be happy to write more if needed.

2

does "abc.txt" exist?
does is need to be "created"?

3

Are you using an ESP32? If so, this will help: Std::fstream with ESP32 - #4 by maxgerhardt - espressif32 - PlatformIO Community

4

It does not exists. It needs to be created new. I think the probable reason could be of non-availability of the file system on my(esp) processor.

5

Thanks for the pointer man. Cheers!

6

"open" typically fails if the file doesn't exist. there's probably a CREATE option, for when a file is written to for the first time

7

I tend to use append instead of open for file creation. With append if the file does not exist then create it and then open it for append.

8

Hi gcjr,

Thanks for the reply.

Open does not mean that it is opening in read mode. It can also open in write mode as well, depending on the options you pass.

9

Thanks Idahowalker. I think the reason is the non-availability of the file system at the esp processor system.

10

and those options include create/append for when a file may not exist

11

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