Problem with sscanf for reading string

Hi

I am trying to scan a string using the code below. I can scan the integers, but not the strings. Could you please give a hint? I defined the string "day" in the beginning, and I am trying to scan the code by adding values to serial monitor. My input values in serial monitor is with the following format:

12,Monday

I have noticed that when I add 2-3 characters, the returned value in serial monitor is empty, and when I add 6-7 characters (let's say Monday), there is a huge amount of rubish text appearing in the serial monitor.

// Example 2 - Receive with an end-marker
#include <String.h>

int hour = 0;
int minute ;
String day ;
String str = "A String";

const byte numChars = 32;
char receivedChars[numChars];   // an array to store the received data

boolean newData = false;

void setup() {
    Serial.begin(9600);
    Serial.println("<Arduino is ready>");
}

void loop() {
    recvWithEndMarker();
    showNewData();
}

void recvWithEndMarker() {
    static byte ndx = 0;
    char endMarker = '\n';
    char rc;
    
    while (Serial.available() > 0 && newData == false) {
        rc = Serial.read();

        if (rc != endMarker) {
            receivedChars[ndx] = rc;
            ndx++;
            if (ndx >= numChars) {
                ndx = numChars - 1;
            }
        }
        else {
            receivedChars[ndx] = '\0'; // terminate the string
            ndx = 0;
            newData = true;
        }
    }
}

void showNewData() {
    if (newData == true) {

       sscanf(receivedChars, "%d,%s", &hour,&day);
        Serial.print("This just in ... ");
        Serial.println(hour);

        Serial.println(day);
        Serial.println(str);

        newData = false;
    }
}
   sscanf(receivedChars, "%d,%s", &hour,&day);

day is a String, not a string.
%s works for strings, but not Strings

  char day[16] ;

  ...
    sscanf(receivedChars, "%d,%s", &hour, day);

Hi

Thank you very much, I did not know that string is different from String. As you both mentioned, I changed it to char and it works like a charm. Thanks .