Remove unwanted characters from char type

Question

I'm working on an ESP8266 module that needs to fetch date data from worldtimeapi, everything works fine but the problem is How do I strip of the time field off the datetime JSON response without loop.

Note: Arduino JSON library was used in deserializing the response data and it seems the library only supports char data type.

void loop ()
{
 // Initialize the request object
 HTTPClient request;
 
// Make a http request
 request.begin(dateTime);
 delay(2000);
 // Check the request status code.
int responseCode = request.GET(); //Get the api host response code.
 Serial.print("Response code is: ");
 Serial.println(responseCode);
 if (responseCode == 200); // If the server returned OK
 {
 String responseData = request.getString();
 Serial.println("Response from the server is:");
 Serial.println(responseData);
 // Deserialize the JSON response data
 StaticJsonDocument<715> result; // Declare data storage to stack
 
 //Check for error during data deserialization
 DeserializationError error = deserializeJson(result, responseData);
 
 if (error) 
 {
 Serial.print(F("Response deserialization failed with reason: "));
 Serial.println(error.f_str());
 return;
 }
 else
 {
 char abbreviation = result["abbreviation"]; // Returns the current time zone abbreviation
 char timezone = result["timezone"]; // Returns the current time zone 
 char datetime = result["datetime"]; // "2021年03月12日T17:04:0
 char date = datetime.remove(9,22); // This line throws error : request for member 'remove' in 'datetime', which is of non-class type 'char'
 
 
 Serial.print("Current time is ");
 Serial.print(datetime);
 Serial.print(" ");
 Serial.print(abbreviation);
 Serial.print(" "); 
 Serial.println(timezone);
 delay(2000);
 }
 
 }
}

• jsotola: why without loop?

Answer 1

You can use strtok to split the string on the T character:

char *datepart = strtok(datetime, "T");
char *timepart = strtok(NULL, "T");
Serial.print("The current date is: ");
Serial.println(datepart);
Serial.print("The current time is: ");
Serial.println(timepart);

An alternative is to just find the T and turn it into the NULL terminating character:

char *T = strchr(datetime, 'T');
*T = 0;

---

If you need to copy the string data into a temporary string first you can do:

char temp[strlen(datetime)+1];
strcpy(temp, datetime);

Then operate on temp instead of datetime.

• Ruby: I need to get rid of T17:04:0.
• Majenko: Then just use datepart.
• Ruby: How do I do that in C++, I think datepart is a SQL syntax.
• Majenko: I have shown you how to do it.
• Majenko: You may need to copy the string content to a temporary work string first then.