Conversion from 'const char*' to 'char'

tetsuochat · July 31, 2021, 5:23pm

Hello i have problem t

To understand this problem, i want to save in a variable the date that i get from the function printLocalTime to use it after to create a file with the date on a SD card, but i don't know how i can do this on the following line :

char date= ('const char(&timeinfo, "%F")');

Here under i put the more complete code for better understanding thanks :

void printLocalTime(){
                            struct tm timeinfo;
                            if(!getLocalTime(&timeinfo)){
                            Serial.println("Failed to obtain time");
                            return;
                            }
  Serial.print("Day of week: ");
  Serial.println(&timeinfo, "%A");
  Serial.print("Month: ");
  Serial.println(&timeinfo, "%m");
  Serial.print("Day of Month: ");
  Serial.println(&timeinfo, "%d");
  Serial.print("Year: ");
  Serial.println(&timeinfo, "%Y");
  Serial.print("Hour: ");
  Serial.println(&timeinfo, "%H");
  Serial.print("Minute: ");
  Serial.println(&timeinfo, "%M");
  Serial.print("Second: ");
  Serial.println(&timeinfo, "%S");
  Serial.print ("Il est exactement : ");
  Serial.print(&timeinfo, "%X");
  Serial.println (" Heures");
  Serial.print("Nous sommes en : ");
  Serial.println(&timeinfo, "%F");                            
  char date= ('const char(&timeinfo, "%F")'); // OBJECTIF / Obtenir la date pour écriture sur carte SD
  Serial.print ('date');                         
                            }
void loop(){
printLocalTime();//Appel de la fonction printLocalTime  
appendFile(SD, "/hello.txt", "World!\n");
delay (1000);
appendFile(SD, "/hello.txt", "HH\n");
delay (1000);
appendFile(SD, "/hello.txt", "BB ");
delay (1000);
appendFile(SD, "/hellolol.txt", "BB ");
Serial.print (date);

anon73444976 · July 31, 2021, 5:30pm

Yours, or ours?

Can you explain this, please?

Serial.println(&timeinfo, "%A");

Please remember to use code tags when posting code.

groundFungus · July 31, 2021, 5:31pm

Read the forum guidelines to see how to properly post code.
Use the IDE autoformat tool (ctrl-t or Tools, Auto format) before posting code in code tags.

The code is not complete. Post the complete code or a minimal verifiable code that exhibits the fault.

tetsuochat · July 31, 2021, 5:33pm

Sorry i am french and i don' undersatnd your question Yours, or ours... what are you talking about ?
i have tried tu put the code between < > but i think i miss something sorry

anon73444976 · July 31, 2021, 5:36pm

There is a francophone forum.

What I meant was "Was the code for our (other forum users) better understanding, or for your better understanding? Because it didn't really help"

tetsuochat · July 31, 2021, 5:36pm

Ok i just learn the ctrl-t
ok the complete code

//Variable communication carte SD
#include "FS.h"
#include "SD.h"
//END

//Variable gestion WIFI, Date et Heure
#include <WiFi.h>
#include "time.h"
const char* ssid     = "XXXXX";
const char* password = "XXXXXX";
const char* ntpServer = "pool.ntp.org";
const long  gmtOffset_sec = 0;
const int   daylightOffset_sec = 3600;
String date;
//END

void removeDir(fs::FS &fs, const char * path) {
  Serial.printf("Removing Dir: %s\n", path);
  if (fs.rmdir(path)) {
    Serial.println("Dir removed");
  } else {
    Serial.println("rmdir failed");
  }
}

void appendFile(fs::FS &fs, const char * path, const char * message) {
  Serial.printf("Tentative ajout au fichier: %s\n", path);

  File file = fs.open(path, FILE_APPEND);
  if (!file) {
    Serial.println("Echec ouverture fichier pour ajout");
    return;
  }
  if (file.print(message)) {
    Serial.println("Ecriture fichier reussi");
  } else {
    Serial.println("Echec écriture fichier");
  }
  file.close();
}

void deleteFile(fs::FS &fs, const char * path) {
  Serial.printf("Deleting file: %s\n", path);
  if (fs.remove(path)) {
    Serial.println("File deleted");
  } else {
    Serial.println("Delete failed");
  }
}

void setup() {
  Serial.begin(9600);
  // Connect to Wi-Fi
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.println("Tentative de connexion...");
  }
  Serial.println("");
  Serial.println("WiFi connected.");

  // Init and get the time
  configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);
  printLocalTime();

  //disconnect WiFi as it's no longer needed
  WiFi.disconnect(true);
  WiFi.mode(WIFI_OFF);

  if (!SD.begin(5)) {
    Serial.println("Card Mount Failed");
    return;
  }
  uint8_t cardType = SD.cardType();

  if (cardType == CARD_NONE) {
    Serial.println("No SD card attached");
    return;
  }

  Serial.print("SD Card Type: ");
  if (cardType == CARD_MMC) {
    Serial.println("MMC");
  } else if (cardType == CARD_SD) {
    Serial.println("SDSC");
  } else if (cardType == CARD_SDHC) {
    Serial.println("SDHC");
  } else {
    Serial.println("UNKNOWN");
  }

  uint64_t cardSize = SD.cardSize() / (1024 * 1024);
  Serial.printf("SD Card Size: %lluMB\n", cardSize);

}
void printLocalTime() {
  struct tm timeinfo;
  if (!getLocalTime(&timeinfo)) {
    Serial.println("Failed to obtain time");
    return;
  }
  Serial.print("Day of week: ");
  Serial.println(&timeinfo, "%A");
  Serial.print("Month: ");
  Serial.println(&timeinfo, "%m");
  Serial.print("Day of Month: ");
  Serial.println(&timeinfo, "%d");
  Serial.print("Year: ");
  Serial.println(&timeinfo, "%Y");
  Serial.print("Hour: ");
  Serial.println(&timeinfo, "%H");
  Serial.print("Minute: ");
  Serial.println(&timeinfo, "%M");
  Serial.print("Second: ");
  Serial.println(&timeinfo, "%S");
  Serial.print ("Il est exactement : ");
  Serial.print(&timeinfo, "%X");
  Serial.println (" Heures");
  Serial.print("Nous sommes en : ");
  Serial.println(&timeinfo, "%F");
  String date = (&timeinfo, "%F"); // OBJECTIF / Obtenir la date pour écriture sur carte SD
  Serial.print ("%F");
}
void loop() {
  printLocalTime();//Appel de la fonction printLocalTime
  appendFile(SD, "/hello.txt", "World!\n");
  delay (1000);
  appendFile(SD, "/hello.txt", "HH\n");
  delay (1000);
  appendFile(SD, "/hello.txt", "BB ");
  delay (1000);
  appendFile(SD, "/hellolol.txt", "BB ");
  Serial.print ('date');


  delay (1000);

}

groundFungus · July 31, 2021, 5:37pm

How to use code tags (</>).

anon73444976 · July 31, 2021, 5:37pm

Please can you explain what this is?

Please remember to use code tags when posting code.

tetsuochat · July 31, 2021, 5:40pm

Ha ok i understand now this is for our (other forum users) to help me on this matter. Thanks

groundFungus · July 31, 2021, 5:41pm

What Arduino board are you using?

Are you sure that you want to broadcast your SSID and password to the world?

tetsuochat · July 31, 2021, 5:42pm

Hi thanks i just understand now how to post it proprely.
I print on serial port the day of the week with %A, this is coming from library time.h with a ntp server

tetsuochat · July 31, 2021, 5:42pm

Ho no !

tetsuochat · July 31, 2021, 5:44pm

This is ESP32 and thanks i modify my code to hide SSID and pass

groundFungus · July 31, 2021, 5:47pm

You should answer the question posed by @ TheMemberFormerlyKnownAsAWOL.

econjack · July 31, 2021, 6:10pm

Try this change:

tetsuochat · July 31, 2021, 6:12pm

Ok but this is working this, my problem is to pass the value to use it latter

anon73444976 · July 31, 2021, 6:20pm

Look

char date= ('const char(&timeinfo, "%F")');

Is just silly - the single quotes make no sense.

Can you please just answer my earlier question?

J-M-L · July 31, 2021, 6:20pm

what is "this"?

tetsuochat · July 31, 2021, 6:22pm

Sorry i have problem to follow i answer allready no ?

anon73444976 · July 31, 2021, 6:23pm

No, you can't explain it?

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Conversion from 'const char*' to 'char'

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