warning: ISO C++ forbids converting a string constant to 'char*

Projects Programming
1

This program I wrote earlier this year was working fine, now I keep getting this warning:

warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]

tmrpcm.play("caillou_0.wav");

Since this is a warning and not necessarily an error, I don't know if it is the reason the program no longer works.
The files are all saved on a microSD card as smaller files 8 bit 16000 sample rate mono files.

The complete code is here:

#include "SD.h"  //need to include the SD library
#define SD_ChipSelectPin 4 //using digital pin 4 o n arduino UNO
#include "TMRpcm.h"  //also need to include this library
#include "SPI.h"

TMRpcm tmrpcm;

int switchPin1 = 2; // the pin where the NO switch will be wired
int switchPin2 = 3; // the pin where the NO switch will be wired
int switchPin3 = 10; // the pin to read if ignition is fully on
int switchPin4 = A0; //the pin to read if sound button is pushed
//int switchPin5 = 10; // the pin to read if sound is pushed
int led1 = 6; //the led that will be lit by the NC switch
int led2 = 7; // the led that will be lit by the NO switch
int led3 = 8; //blue led
int switchState1 = 0;  //the state of the NC switch
int switchState2 = 0;  //the state of the NO switch
int switchState3 = 0; //the state of the ignition switch
int switchState4 = 0; // the state of the Siren Switch
int switchState5 = 0; // the state of other siren switch
void setup() {
  // put your setup code here, to run once:
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(switchPin1, INPUT_PULLUP);
  pinMode(switchPin2, INPUT_PULLUP);
  pinMode(switchPin3, INPUT_PULLUP);
  pinMode(switchPin4, INPUT_PULLUP);
//    pinMode(switchPin5, INPUT);

  tmrpcm.speakerPin = 9; 

  if (!SD.begin(SD_ChipSelectPin)) {  //see if the card is present and can be initialized:
  return; //don't do anything more if not  
    }
  tmrpcm.volume(5);
  tmrpcm.play("peppa_pig.wav"); //the sound file will play each time the arduino powers up or is reset
}

void loop() {
  // put your main code here, to run repeatedly:
  switchState1 = digitalRead(switchPin1);
  switchState2 = digitalRead(switchPin2);
  switchState3 = digitalRead(switchPin3);
  switchState4 = digitalRead(switchPin4);
//  switchState5 = digitalRead(switchPin5);
  {

  if (switchState1 ==   LOW) {  //if switch is pushed
    tmrpcm.play("peppa_pig.wav");
    digitalWrite(led1,HIGH);
    digitalWrite(led2,LOW) ;
    delay(1000);
  }
  if (switchState2 == LOW) { //if switch is pushed
    tmrpcm.play("caillou_0.wav");
    digitalWrite(led2, HIGH);
    digitalWrite(led1, LOW);
    delay(1000);}

  if (switchState3 == LOW) {//if sw3 is pushed then play "2.wav"
    tmrpcm.play("blaze_horn.wav");
    for (int j=1; j<=160; j=j+1) {digitalWrite(led1, HIGH);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
    delay(100);
    digitalWrite(led1, LOW);
    digitalWrite(led3, HIGH);
    delay(100);    
  }
  digitalWrite(led1, LOW);
  digitalWrite(led3, LOW); 
  }
  if (switchState4 == LOW) {//if sw4 is pushed play "3.wav"
    tmrpcm.play("pj_masks_theme.wav");
    for (int k=1; k<=35; k=k+1) {digitalWrite(led1, HIGH);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
    delay(200);
    digitalWrite(led1, LOW);
    digitalWrite(led2, HIGH);
    digitalWrite(led3, LOW);
    delay(200);
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, HIGH);
    delay(200);
    }
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
 
  }
  }
}
2

Ignore it. As long as you don't try to change the string in the function it'll work fine.

The more aggressive code people will be uphappy about things like this but it'll still work.

-jim lee

3

tmrpcm.play((char *)"caillou_0.wav");

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