"empty character constant" compile error

Using Arduino Programming Questions
#1

This program from How To Test The SPI Module Of Arduino- (Part 32/49) gives a compile error (“empty character constant”) at this line:

for(i = 0; outByte !=’’; i ++)
The ‘’ are really two separate ', not a single".
What do I overlook?
```
*#include <SPI.h>                                                  // including the SPI library
char outByte [20] = “ENGINEERS GARAGE”;                           // string to be send and received via SPI port
int led = 6;                                                      // variable which holds the pin number at which the LED is attached
char inByte;                                                      // variable which stores the value of the byte received from SPI bus
int i = 0;

void setup()
{
  pinMode(led, OUTPUT);                                           // setting the LED pin as output
  Serial.begin(9600);                                             // initializing the serial port at 9600 baud rate
  SPI.begin();                                                    // initialize the SPI port as master
  delay(100);  
}

void loop()
{    
  digitalWrite(led, HIGH);          
  for(i = 0; outByte [i] !=’’; i ++)                            // send and receive the bytes of the string
  {
    inByte = SPI.transfer(outByte [i]);
    Serial.write(inByte);   
  }
  Serial.println();
  delay(1000);
  digitalWrite(led, LOW);
  delay(1000);  
}*
```

#2

well you need something in between the quotes :slight_smile:
what do you want to test ? if outByte is empty ? it's impossible, a byte in memory will always have a content.

if you want to test for a null char then use '\0'

#3

Thank you!

That solved it: /0

#4

Good

(it’s « anti-slash », not « slash » though: ‘\0’)

#5