Kompilacja i błąd char* C++

Question

Witajcie.
W jaki sposób można rozwiązać taki komunikat

warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]

             gprs.sendSMS (buffNumber, "Relay 1 Status Aktif");
 

podczas kompilacji tego kodu:
 

#include <gprs.h>
#include <softwareserial.h>

#define TIMEOUT    5000
#define AKTIF LOW
#define MATI HIGH

byte Relay[] = {A0,A1,A2,A3};
byte StatRelay[4];
char buffNumber[20];
char currentLine[500] = "";
int currentLineIndex = 0;
bool nextLineIsMessage = false;
String replyNumber = "0799800990";
GPRS gprs;

void setup() {
  for(int i=0; i < 4; i++) {
    pinMode (Relay[i] , OUTPUT); 
    digitalWrite (Relay[i], MATI); 
    StatRelay[i] = MATI;
  } 
  Serial.begin(9600);
  while (!Serial);
  Serial.println("Aktifkan SIM800L V2 >>> Otomatis Membaca SMS");
  gprs.preInit();
  delay(1000);
  while (0 != gprs.init()) {
    delay(1000);
    Serial.print("init errorrn");
  }
  // Mengatur SMS ke mode ASCII
  if (0 != gprs.sendCmdAndWaitForResp("AT+CMGF=1rn", "OK", TIMEOUT)) {
    ERROR("ERROR:CNMI");
    return;
  }
  // Membaca SMS yang Baru Masuk
  if (0 != gprs.sendCmdAndWaitForResp("AT+CNMI=1,2,0,0,0rn", "OK", TIMEOUT)) {
    ERROR("ERROR:CNMI");
    return;
  }
  int pjg = replyNumber.length() + 1;
  buffNumber[pjg];
  replyNumber.toCharArray(buffNumber,pjg);
  Serial.print("Kirim balasan ke nomor = > ");
  Serial.println(buffNumber);
  Serial.println("Initialisasi Berhasil");
  Serial.println("=============================================================");
}

void loop() {
  // Merubah status Relay ON / OFF
  for(int i=0; i < 4; i++) {
    digitalWrite(Relay[i], StatRelay[i]);
  } 
  
  // Jika terdapat data masukan dari SIM800
  if (gprs.serialSIM800.available()) {
    char lastCharRead = gprs.serialSIM800.read();
    // Simpan semuad data pada lastCharRead, kemudian jika terdapat r atau n, sebagai tanda akhir pesan masuk
    if (lastCharRead == 'r' || lastCharRead == 'n') {
      String lastLine = String(currentLine);

      //Jika pesan terakihr +CMT menandakan pesan barus diterima
      if (lastLine.startsWith("+CMT:")) {
        Serial.println(lastLine);
        nextLineIsMessage = true;

      } else if (lastLine.length() > 0) {
        if (nextLineIsMessage) {
          Serial.println(lastLine);
          // ================================================================>> Fungsi Mengendalikan Relay
          //Kendali Relay 1
          if (lastLine.indexOf("Relay 1 ON") >= 0) {
            StatRelay[0] = AKTIF;
            Serial.print("Balasan  ====>>>>  ");
            Serial.println("Relay 1 Status Aktif");
            gprs.sendSMS (buffNumber, "Relay 1 Status Aktif");
          }
          else if (lastLine.indexOf("Relay 1 OFF") >= 0) {
            StatRelay[0] = MATI;
            Serial.print("Balasan  ====>>>>  ");
            Serial.println("Relay 1 Status Mati");
            gprs.sendSMS (buffNumber, "Relay 1 Status Mati");
          }
          //Kendali Relay 2
          if (lastLine.indexOf("Relay 2 ON") >= 0) {
            StatRelay[1] = AKTIF;
            Serial.print("Balasan  ====>>>>  ");
            Serial.println("Relay 2 Status Aktif");
            gprs.sendSMS (buffNumber, "Relay 2 Status Aktif");
          }
          else if (lastLine.indexOf("Relay 2 OFF") >= 0) {
            StatRelay[1] = MATI;
            Serial.print("Balasan  ====>>>>  ");
            Serial.println("Relay 2 Status Mati");
            gprs.sendSMS (buffNumber, "Relay 2 Status Mati");
          }
          //Kendali Relay 3
          if (lastLine.indexOf("Relay 3 ON") >= 0) {
            StatRelay[2] = AKTIF;
            Serial.print("Balasan  ====>>>>  ");
            Serial.println("Relay 3 Status Aktif");
            gprs.sendSMS (buffNumber, "Relay 3 Status Aktif");
          }
          else if (lastLine.indexOf("Relay 3 OFF") >= 0) {
            StatRelay[2] = MATI;
            Serial.print("Balasan  ====>>>>  ");
            Serial.println("Relay 3 Status Mati");
            gprs.sendSMS (buffNumber, "Relay 3 Status Mati");
          }
          //Kendali Relay 4
          if (lastLine.indexOf("Relay 4 ON") >= 0) {
            StatRelay[3] = AKTIF;
            Serial.print("Balasan  ====>>>>  ");
            Serial.println("Relay 4 Status Aktif");
            gprs.sendSMS (buffNumber, "Relay 4 Status Aktif");
          }
          else if (lastLine.indexOf("Relay 4 OFF") >= 0) {
            StatRelay[3] = MATI;
            Serial.print("Balasan  ====>>>>  ");
            Serial.println("Relay 4 Status Mati");
            gprs.sendSMS (buffNumber, "Relay 4 Status Mati");
          }
          nextLineIsMessage = false;
        }
        // ==================================================================>>
      }

      //Clear char array for next line of read
      for ( int i = 0; i < sizeof(currentLine);  ++i ) {
        currentLine[i] = (char)0;
      }
      currentLineIndex = 0;
    } 
    else {
      currentLine[currentLineIndex++] = lastCharRead;
    }
  }
}

 

Answer 1

String jest immutable. Poczytaj co to znaczy WIĘC nie możesz go zmienić.

 A literał jest niestety const - typu stałego stąd nie możesz go zamienić na *char.

Posłużę się rozwinięciem STACKA: 

This is an error message you see whenever you have a situation like the following:

char* pointer_to_nonconst = "string literal";

Why? Well, C and C++ differ in the type of the string literal. In C the type is array of char and in C++ it is constant array of char. In any case, you are not allowed to change the characters of the string literal, so the const in C++ is not really a restriction but more of a type safety thing. A conversion from const char* to char* is generally not possible without an explicit cast for safety reasons. But for backwards compatibility with C the language C++ still allows assigning a string literal to a char* and gives you a warning about this conversion being deprecated.

So, somwehere you are missing one or more consts in your program for const correctness. But the code you showed to us is not the problem as it does not do this kind of deprecated conversion. The warning must have come from some other place.

Answer 2

Daj jawne rzutowanie literałów tekstowych: gprs.sendSMS (buffNumber, (char*)"Relay 1 Status Aktif");