Using a HashMap to store the sensor addresses with tempetures on Arduino - arduino

Question

I have started a small project to hopefully replace RPis running a Java library with Arduinos.
(I am normally working with Java, so not as familiar with C)
There are multiple temp sensors connected to the board. I read the values and want to store them with a reference to the sensor address. When a value changes, an update of all the sensors with their address and the temperatures is send to the server (hence I need the store to compare the values every 10 seconds).
I am trying to use the HashMap from Arduino Playground, as on a first look it seemed to do what I need and seems lightweight.
However, when reading the address of the temp sensor from a variable from the HashMap it doesn't return the right one (when there is some data pre-set in the hashmap):
int strLen = sAddress.length();
char *cAddress = (char *)malloc(strLen+1);
sAddress.toCharArray(cAddress, strLen+1);
byte position = sensorHashMap.getIndexOf(cAddress);
However, if I replace the *cAddress with:
char *cAddress = "28aae25501412c";
it does find it. So what am I doing wrong?
My approach to store the temp values with the address as a reference might not be the best, and it seems that the code crashes later on when trying to update the value but I haven't gone down that far yet. If there is a better solution than I am very open to some suggestions off course.
The full code below:
#include <HashMap.h>
#include <OneWire.h>
#include <ESP8266WiFi.h>
#include <DS18B20.h>
char wifiSSID[] = "xxxx";
char wifiPassword[] = "xxxx";
unsigned long lastTempCheck = 0;
const byte HASH_SIZE = 10; // Max 10 (temp) sensors etc
HashType<char*, float> hashRawArray[HASH_SIZE];
HashMap<char*, float> sensorHashMap = HashMap<char*, float>( hashRawArray , HASH_SIZE );
int sensorsRegistered = 1;
WiFiClient client;
DS18B20 ds(5); // Is D1
void setup()
{
Serial.begin(115200);
Serial.println();
WiFi.begin(wifiSSID, wifiPassword);
Serial.print("Connecting");
while (WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println("---");
Serial.println("Connected to wifi");
Serial.print("Connected, IP address: ");
Serial.println(WiFi.localIP());
Serial.println("Setup completed, ready to run...");
// Test data
sensorHashMap[0]("name", 18);
sensorHashMap[1]("test", 200);
sensorHashMap[2]("qwer", 1234);
sensorHashMap[3]("28fffa6f51164ae", 123);
sensorHashMap[4]("28aae25501412c", 456);
}
void loop() {
// Duty cycle of the application
delay(100);
if ((millis() < lastTempCheck) || (millis() - lastTempCheck > 1000 * 10)) {
// Verifying the HashMap works with the pre-set values.
Serial.print("Checking pre-set values: ");
Serial.println( sensorHashMap.getIndexOf("28fffa6f51164ae"), DEC );
Serial.print("Checking sensor value: ");
Serial.println( sensorHashMap.getValueOf("28fffa6f51164ae") );
while (ds.selectNext()) {
float temp = ds.getTempC();
uint8_t address[8];
ds.getAddress(address);
String sAddress = "";
for (uint8_t i = 0; i < 8; i++) {
sAddress += String(address[i], HEX);
}
int strLen = sAddress.length();
char *cAddress = (char *)malloc(strLen+1);
sAddress.toCharArray(cAddress, strLen+1);
//char *cAddress = "28aae25501412c";
byte position = sensorHashMap.getIndexOf(cAddress);
Serial.print("Position: ");
Serial.println( position);
Serial.println( sensorHashMap.getIndexOf(cAddress), DEC );
if (position < HASH_SIZE) {
Serial.print("Updating sensor value, currently: ");
Serial.println( sensorHashMap.getValueOf(cAddress));
sensorHashMap[position](cAddress, temp); //ds.getTempC()
} else {
Serial.print("Creating sensor value, id is going to be ");
Serial.println(sensorsRegistered);
sensorHashMap[sensorsRegistered](cAddress, temp);
sensorsRegistered++;
}
free(address);
}
lastTempCheck = millis();
}
}