Force binary number display Signed Integer?

Question

The binary representation of number 53 is 0b00110101 and -53 is 11001010.

I used 1's complement of 53 to get the binary value of -53.

But when i try to print those binary number as

print(0b00110101) //53
print(0b11001010) //-53

I get the following output.

53

202

How can i make the compiler return the negative representation of the binary value?

Note that the (8-bit) 2's complement of 00110101 is 11001011, not 11001010. — Martin R
– Martin R, Commented Jul 5, 2017 at 17:42

Martin R · Accepted Answer · 2017-07-05 17:57:57Z

4

0b11001010 is an integer literal and in print(0b11001010) its type is Int and the value is 202.

But you can create a signed 8-bit value with the same bit pattern:

let x = Int8(bitPattern: 0b11001010)
// Equivalent to:
// let x = Int8(bitPattern: 202)
print(x) // -54

using the Int8(bitPattern:) initializer:

Creates a new instance with the same memory representation as the given value.

(Here the compiler infers the type of the integer literal as UInt8.)

answered Jul 5, 2017 at 17:39

Martin R

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1 Comment

Thanks..but my head started spinning now :)