What does signed and unsigned values mean?

Question

What does signed mean in C? I have this table to show:

Th

Answer 1

The table is missing the minuses. The range of signed char is -128 to +127; likewise for the other types on the table.

Answer 2

It was a typo in the book; signed char goes from -128 to 127.

Signed integers are stored using the two's complement representation, in which the first bit is used to indicate the sign.

In C, chars are just 8 bit integers. This means that they can go from -(2^7) to 2^7 - 1. That's because we use the 7 last bits for the number and the first bit for the sign. 0 means positive and 1 means negative (in two's complement representation).

• The biggest positive 7 bit number is (01111111)b = 2^7 - 1 = 127.
• The smallest negative 7 bit number is (11111111)b = -128
  (because 11111111 is the two's complement of 10000000 = 2^7 = 128).

Unsigned chars don't have signs so they can use all the 8 bits. Going from (00000000)b = 0 to (11111111)b = 255.

Answer 3

Signed numbers are those that have either + or - appended with them. E.g +2 and -6 are signed numbers. Signed Numbers can store both positive and negative numbers thats why they have bigger range. i.e -32768 to 32767

Unsigned numbers are simply numbers with no sign with them. they are always positive. and their range is from 0 to 65535.

Hope it helps

Answer 4

Signed usually means the number has a + or - symbol in front of it. This means that unsigned int, unsigned shorts, etc cannot be negative.

Answer 5

A signed integer can have both negative and positive values. While a unsigned integer can only have positive values.

For signed integers using two's complement , which is most commonly used, the range is (depending on the bit width of the integer):

char s -> range -128-127

Where a unsigned char have the range:

unsigned char s -> range 0-255

Answer 6

First, your table is wrong... negative numbers are missing. Refering to the type char.... you can represent at all 256 possibilities as char has one byte means 2^8. So now you have two alternatives to set ur range. either from -128 to +128 or 0 to 255. The first one is a signed char the second a unsigned char. If you using integers be aware what kind of operation system u are using. 16 bit ,32 bit or 64 bit. Int (16 bit,32 bit,64 bit). char has always just 8 bit value.