A character string is NUL terminated.

An array of binary values has no terminator. Entries may be any value within the range of the data type chosen.

 

I'll have a go when I get home.

What would happen if you actually wanted an array of numbers. If one of the numbers stored in the array way 0, would the C routine that has the: while(*characters) nit think that it was the end of the array when it got to a number 0 which you may actually want stored in the array.

No! The character for the number 0 and the nul character are two different values.

The character for the number 0 is represented by 0x30.
The nul character is represented by 0x00.

Hence, it is easy for the C program to tell the difference.

The number 100.0 would be represented in your code as:

str[0]=0x31;
str[1]=0x30;
str[2]=0x30;
str[3]=0x2E;
str[4]=0x30;
str[5]=0x00;

Play computer and visually scan through the characters in this string. You can easily see the end of the string without confusing it with the character '0'.

By the way, I like The_RB's suggestion. It makes for more readable code. I didn't use it in my example because I wanted to highlight the difference in ASCII values for '0' and nul.

 

Thanks for everyone's help.

Putting a 6 instead of 5 worked in the declaration of str.

 

There are a number of fundamental lessons to learn here.
Hope you paid attention to all the details along the way.

str[5] = 0;
str[5] = 0x00;

produce the same thing.

str[4] = '0';
str[4] = 0x30;
str[4] = 48;

produce the same thing.

str[3] = '.';
str[3] = 0x2E;
str[3] = 46;

produce the same thing.

&str[0] is the address of str

char str[6]; // declares the length of the array to have 6 bytes. This includes the terminating NUL (zero byte).

'A' is a character
"A" is a character string

 

Thanks again.

I've been programming assembly language and Objective C for the mac for a few years now, and now that I've moved over to C on the PIC, I'm finding it a little strange how stuff is donr. I know Objective C is derived from C, but it is such a more high level object orientated version.