Transmitting some joystick and switch values with 433mhz transmitter

#include 

#include 

#include 

// Joy stick 1 pins
int Joy_stick_switch_L = 3;
int Joy_stick_X_L = A2;
int Joy_stick_Y_L = A3;

// Joy stck 2 pins
int Joy_stick_switch_R = 2;
int Joy_stick_X_R = A1;
int Joy_stick_Y_R = A0;

// Switch pins
int Switch_top_left = 7;
int Switch_top_right = 5;
int Switch_bottom_left = 6;
int Switch_bottom_right = 4;

RH_ASK rf_driver;

void setup() {
  rf_driver.init();
}

void loop() {
  // Reading Joy stick 1
  float S_L = digitalRead(Joy_stick_switch_L);
  float X_L = analogRead(Joy_stick_X_L);
  float Y_L = analogRead(Joy_stick_Y_L);
  
  // Reading Joy stick 2
  float S_R = digitalRead(Joy_stick_switch_R);
  float X_R = analogRead(Joy_stick_X_R);
  float Y_R = analogRead(Joy_stick_Y_R);

  // Reading the 4 switches 
  float T_L = digitalRead(Switch_top_left);
  float T_R = digitalRead(Switch_top_right);
  float B_L = digitalRead(Switch_bottom_left);
  float B_R = digitalRead(Switch_bottom_right);

  String str_S_L = String(S_L);
  String str_X_L = String(X_L);
  String str_Y_L = String(Y_L);

  String str_S_R = String(S_R);
  String str_X_R = String(X_R);
  String str_Y_R = String(Y_R);

  String str_T_L = String(T_L);
  String str_T_R = String(T_R);
  String str_B_L = String(B_L);
  String str_B_R = String(B_R);

  String str_out = str_S_L + ',' + str_X_L + ',' + str_Y_L + ',' + str_S_R + ',' + str_X_R + ',' + str_Y_R + ',' + str_T_L + ',' + str_T_R + ',' + str_B_L + ',' + str_B_R;

  static char *msg = str_out.c_str();
    
  rf_driver.send((uint8_t *)msg, strlen(msg));
  rf_driver.waitPacketSent();
}

Hi, I am Jack this is my first project using Arduino and c++ so I am defiantly gonna make some stupid mistakes. So I am using an Arduino Uno with a H34S (written on the back of the PCB) as the transmitter, 2 Joysticks (each one has an integrated switch as well as x and y) and 4 switches. I plan to use this to wirelessly control a small robot but first baby steps. I just want to transmit the pot values from the joysticks and the switch values.

I followed the "Using Inexpensive 433MHz Transmit and Receive Modules with Arduino" video and read the article.

The problem i run into iswhen I go to compile the code I get

"invalid conversion from 'const char*' to 'char*' [-fpermissive]"

"static char *msg = str_out.c_str();"

Any help would be greatly apreciated