Problem about convert array of string to char using toCharArray

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2

If you are using the String library you can use standard array logic to access the pointer rather than toCharArray which copies the entire array.

void setup() {
  String data = "123.456";
  char * carray = &data[ 0 ];
  float f = atof( carray  );
  Serial.begin( 9600 );
  Serial.print( f, 5 );
}

void loop() {}

The alternative using toCharArray works like this: ( carray must be an array, or pointer to valid data )

void setup() {
  String data = "123.456";
  
  char carray[ 10 ];
  
  data.toCharArray( carray, 10 );
  
  float f = atof( carray  );
  Serial.begin( 9600 );
  Serial.print( f, 5 );
}

void loop() {}