error: invalid conversion from 'char' to 'char*' [-fpermissive] I have written a simple code to read data from capacitive keypad and display it on LCD.

I am getting the data from keypad in following data structure.

char phoneNumber[PHONE_DIGITS];


and then displaying the data on LCD as 

   LcdString(phoneNumber[i]);


where my LCD string function is 

void LcdString(char *characters)
{
  while (*characters)
  {
    LcdCharacter(*characters++);
  }
}


There is a type cast error 


  error: invalid conversion from 'char' to 'char*' [-fpermissive]


How can I debug it?
You're calling your function with a single char, specified by phoneNumber[i], but your function is expecting an array.

If you change your call to:

LcdString(phonenumber)


then that will pass the entire array.

Are you trying to say that you're storing multiple phone numbers?  i.e. a two dimensional array?  Check out the String reference for more details: https://www.arduino.cc/en/Reference/String