How to define an array of binary 8 bit numbers in keil?

Tanmay_Karmakar · Aug 30, 2020

I've tried putting suffix 'y' followed by binary numbers within an array in header file but "syntax error near 'y', expected '}' " appear. Kindly ignore the first array of the attachment.

Code:

extern unsigned int A[8]={
00111100y,
01100110y,
01100110y,
01111110y,
01100110y,
01100110y,
01100110y};

Pommie · Aug 30, 2020

The highlighted line in the attachment has an extra comma.

Mike.
BTW, code tags are [code] and [/code]

Tanmay_Karmakar · Aug 30, 2020

Pommie said:
The highlighted line in the attachment has an extra comma.

Mike.
BTW, code tags are [code] and [/code]

Ok.. kindly ignore the first array of the attachment, it was just some trial. I need the following type as mentioned in my description.

Pommie · Aug 30, 2020

Try prefixing 0b to the number I.e. 0b0001111 =15 decimal.

Mike.

Tanmay_Karmakar · Aug 30, 2020

Pommie said:
Try prefixing 0b to the number I.e. 0b0001111 =15 decimal.

Mike.

I've tried.. but in keil it is a constant for octal numbers.. so I searched for keil constants found y or Y suffix for binary representation.

Keil constants

Pommie · Aug 30, 2020

Can you post the code that gives the error?

Mike.

Tanmay_Karmakar · Aug 30, 2020

I just gave one in the description. Kindly look at the attachment carefully. You will see corresponding to which lines the errors are being generated.

Pommie · Aug 30, 2020

Shouldn't variables declared as extern be define elsewhere, externally even.

Mike.
Btw, should you be using unsigned char for 8 bit numbers?

Tanmay_Karmakar · Aug 30, 2020

Yes, of course, it's a header file, it's not the main program. It's just for definition of some bit mapped array variables. And yes I've tried unsigned char data type also. If you have keil installed perhaps you can try and solve it with just one array in the header file and a main c program file to call it.

Pommie · Aug 30, 2020

I don't have Keil installed but extern means it defined in another C file. Get rid of the extern and move it into the main C file and it should compile.

Mike.

Ian Rogers · Aug 31, 2020

The way extern works is you define it in another C file and use it in the current file... If you define in a header and call said header then the word extern must be omitted..

Tanmay_Karmakar · Sep 5, 2020

Thank you all for taking your time.. but all the fixes you have mentioned are known to me and aren't the issues, works fine with decimal numbers. My concern is to write array of binary numbers like

Code:

 unsigned char A[]={ 01101100, 00110110}

. In keil binay specifier is 'y' as suffix and '0' as prefix is octal specifier. So if I write

Code:

 01101100y

there's a conflict for compiler whether the number is binary or octal. So I can't find other ways to specify binary numbers followed by zero. That's what I want a solution to...

rjenkinsgb · Sep 6, 2020

From the a post on the Keil site:

ANSI C does not have any syntax for specifying binary integer literals. Decimal, octal, hex; no binary.

The Keil compiler is based on ANSI C, which has no way of accepting binary values.

Some compiler makers add their own non-standard ways but Keil have not.

You must use hex instead.

Ian Rogers · Sep 6, 2020

Use hex... All compilers use 0x00 format.. its the best binary shorthand...

Tanmay_Karmakar said:
unsigned char A[]={ 01101100, 00110110}

becomes
unsigned char A[]={ 0x6C, 0x36}... ie 0110 (6) and 1100 (C)... I rarely use binary I'm far more comfortable with hex...

Ian Rogers · Sep 6, 2020

After lots of google work.. uVision is based on the GNU complier.. Mike is indeed correct.. This is from the GNU manual

gnu said:
i = 42;
i = 0x2a;
i = 052;
i = 0b101010;

These are the same.

Tanmay_Karmakar · Sep 7, 2020

rjenkinsgb said:
From the a post on the Keil site:

The Keil compiler is based on ANSI C, which has no way of accepting binary values.

Some compiler makers add their own non-standard ways but Keil have not.

You must use hex instead.

Keil constants
Kindly take a look at this..

Tanmay_Karmakar · Sep 7, 2020

rjenkinsgb said:
From the a post on the Keil site:

The Keil compiler is based on ANSI C, which has no way of accepting binary values.

Some compiler makers add their own non-standard ways but Keil have not.

You must use hex instead.

Keil constants
Kindly take a look at this..

Tanmay_Karmakar · Sep 7, 2020

Ian Rogers said:
Use hex... All compilers use 0x00 format.. its the best binary shorthand...

becomes
unsigned char A[]={ 0x6C, 0x36}... ie 0110 (6) and 1100 (C)... I rarely use binary I'm far more comfortable with hex...

In my case using hex is better than using decimal but then again for my project I need binary map of 8by8 matrix. And I tried using '0b' prefix, didn't work.

gophert · Sep 7, 2020

Tanmay_Karmakar said:
In my case using hex is better than using decimal but then again for my project I need binary map of 8by8 matrix. And I tried using '0b' prefix, didn't work.

the 0 (zero) prefix is only an octal indicator if no suffix is present. If a Y suffix is present, it is binary.
Also, try with no leading zeros in your binary if it is not working with leading zero. If neither work, then you have some issue with other code.

Ian Rogers · Sep 8, 2020

Here's what I do...

unsigned char matrix[] = {
0xE9, // 11101001
0xA9, // 101010001
0x55, // 01010101
0x46, // 01000110
0x77 // 01110111
};

Thererin you can still see the map..

How to define an array of binary 8 bit numbers in keil?

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