[C] Learning Byte and Bit in Language C

I am learning developing in C now. So I have to understand byte and bit.
As I recognized it, I will write down about these things. I hope to help you to understand it.

Bit

A bit represents 0 or 1. It usually used as base-2 number system.
Here is an example table.

You found that 4 bit can represent from 0 to 15 in decimal.
So it can represents type of 16 number.

By the way hexadecimal is base-16 number system.
In C, it is written with prefix 0x. Let’s add hexadecimal column to above table.

Byte

Byte usually represents 8 bit.
Can you understand how it can represents decimal range?
I said 4 bit represents from 0 to 15 In previous paragraph.
As 8 bit equals 4 bit add 4 bit, it is calculated by below expression.
16 * 16 = 256
So 8 bit can represent from 0 to 255 in decimal, and type of 256 number.

Let’s expand previous table until 8 bit.

Mmm, it seems difficult at a glance. But it is easy to understand if you read it little by little.
Let’s look into decimal 64.

First I split binary to two parts. I make each part 4 bit.
100 – 0000
The left part is 100. It is represented 0×4 in hexadecimal.
The right part is 0000. It is represented 0×0 in hexadecimal.
So in hexadecimal, it is represented 0×40.

ASCII Table

ASCII table is character code table.
>> ASCII Table and Description

Let’s add this ASCII code column to previous table we made.

Over decimal 127, there seem to be several type of extended ASCII table.
So I didn’t write character.

Let’s look into row of character ‘A’.

Character ‘A’ is equal to decimal 65, and hexadecimal 0×41.

Character and int in language C

Previous paragraph shows you relationship between character code and decimal and hexadecimal.
I show you simple C code.

#include <stdio.h>

int main(int argc, char const *argv[])
{
	char c, c2;
	int i, j;

	c = 'A';
	printf("c is %c. character code is %d, binary is %x\n", c, c, c);
	//output
	//c is A. character code is 65, binary is 41

	i = 97;
	printf("i is %c. character code is %d, binary is %x\n", i, i, i);
	//output
	//i is a. character code is 97, binary is 61

	//char to int
	j = c;
	printf("j is %c. character code is %d, binary is %x\n", j, j, j);
	//output
	//j is A. character code is 65, binary is 41

	//int to char
	c2 = i;
	printf("c2 is %c. character code is %d, binary is %x\n", c2, c2, c2);
	//output
	//c2 is a. character code is 97, binary is 61

	return 0;
}

Over One Byte

You can understand one byte. But it seems you have to use more than one byte in ordinary programming.
So I am going to write down it on next article.