UTF-8の求め方 ビット演算の練習問題

答えは0x5E

CodePointの確認

code:js

'^'.codePointAt(0).toString(16)

//'5e'

'^'.codePointAt(0).toString(10)

//'94'

'^'.codePointAt(0).toString(2)

//'1011110'

求め方に当てはめるとこうなる

code:js

// 00000000

//| 1011110

//----------

// 01011110 => 5eになるはず

ビット演算を使って求める

code:js

('^'.codePointAt(0) | 00000000).toString(2)

//'1011110'

結果

code:js

[

('^'.codePointAt(0) | 00000000)

]

答えは0xD390

CodePointの確認

code:js

'Ӑ'.codePointAt(0).toString(16)

//'4d0'

'Ӑ'.codePointAt(0).toString(10)

//'1232'

'Ӑ'.codePointAt(0).toString(2)

//'10011010000'

求め方に当てはめるとこうなる

code:js

// 11000000 10000000

//| 10011 010000

//---------------------

// 11010011 10010000 => d390になるはず

ビット演算を使って求める

code:js

//下6桁だけほしいから、下6桁だけが1のビット論理積をとる

(('Ӑ'.codePointAt(0) & 0b00111111)).toString(2)

//'10000'

//これと10000000のビット論理和をとる

(('Ӑ'.codePointAt(0) & 0b00111111) | 0b10000000).toString(2)

//'10010000'

//16進数だと0x90

(('Ӑ'.codePointAt(0) & 0b00111111) | 0b10000000).toString(16)

//'90'

//次の5桁、使った6ビット分ずらす

('Ӑ'.codePointAt(0) >> 6).toString(2)

//'10011'

//これと11000000のビット論理和をとる

((('Ӑ'.codePointAt(0) >> 6) & 0b00111111) | 0b11000000).toString(2)

//'11010011'

//16進数だと0xd3

((('Ӑ'.codePointAt(0) >> 6) & 0b00011111) | 0b11000000).toString(16)

//'d3'

結果

code:js

[

((('Ӑ'.codePointAt(0) >> 6) & 0b00111111) | 0b11000000),

(('Ӑ'.codePointAt(0) & 0b00111111) | 0b10000000)

]

答えは0xEFB8B0

CodePointの確認

code:js

'︰'.codePointAt(0).toString(16)

//'fe30'

'︰'.codePointAt(0).toString(10)

//'65072'

'︰'.codePointAt(0).toString(2)

//'1111111000110000'

求め方に当てはめるとこうなる

code:js

// 11100000 10000000 10000000

//| 1111 111000 110000

//----------------------------

// 11101111 10111000 10110000 => efb8b0になるはず

ビット演算を使って求める

code:js

//下6桁

('︰'.codePointAt(0) & 0b00111111).toString(2)

//'110000'

(('︰'.codePointAt(0) & 0b00111111) | 0b10000000).toString(2)

//'10110000'

(('︰'.codePointAt(0) & 0b00111111) | 0b10000000).toString(16)

//'b0'

//次6桁

(('︰'.codePointAt(0) >> 6) & 0b00111111).toString(2)

//'111000'

((('︰'.codePointAt(0) >> 6) & 0b00111111) | 0b10000000).toString(2)

//'10111000'

((('︰'.codePointAt(0) >> 6) & 0b00111111) | 0b10000000).toString(16)

//'b8'

//次4桁

(('︰'.codePointAt(0) >> 12) & 0b00001111).toString(2)

//'1111'

((('︰'.codePointAt(0) >> 12) & 0b00001111) | 0b11100000).toString(2)

//'11101111'

((('︰'.codePointAt(0) >> 12) & 0b00001111) | 0b11100000).toString(16)

//'ef'

結果

code:js

[

((('︰'.codePointAt(0) >> 12) & 0b00001111) | 0b11100000),

((('︰'.codePointAt(0) >> 6) & 0b00111111) | 0b10000000),

(('︰'.codePointAt(0) & 0b00111111) | 0b10000000)

]

答えは0xF09F8084

CodePointの確認

code:js

'🀄'.codePointAt(0).toString(16)

//'1f004'

'🀄'.codePointAt(0).toString(10)

//'126980'

'🀄'.codePointAt(0).toString(2)

//'11111000000000100'

求め方に当てはめるとこうなる

code:js

// 11110000 10000000 10000000 10000000

//| 000 011111 000000 000100

//-------------------------------------

// 11110000 10011111 10000000 10000100 => f09f8084になるはず

ビット演算を使って求める

code:js

//下6桁

('🀄'.codePointAt(0) & 0b00111111).toString(2)

//'100'

(('🀄'.codePointAt(0) & 0b00111111) | 0b10000000).toString(2)

//'10000100'

(('🀄'.codePointAt(0) & 0b00111111) | 0b10000000).toString(16)

//'84'

//次6桁

(('🀄'.codePointAt(0) >> 6) & 0b00111111).toString(2)

//'0'

((('🀄'.codePointAt(0) >> 6) & 0b00111111) | 0b10000000).toString(2)

//'10000000'

((('🀄'.codePointAt(0) >> 6) & 0b00111111) | 0b10000000).toString(16)

//'80'

//次6桁

(('🀄'.codePointAt(0) >> 12) & 0b00111111).toString(2)

//'11111'

((('🀄'.codePointAt(0) >> 12) & 0b00111111) | 0b10000000).toString(2)

//'10011111'

((('🀄'.codePointAt(0) >> 12) & 0b00111111) | 0b10000000).toString(16)

//'9f'

//次3桁

(('🀄'.codePointAt(0) >> 18) & 0b00000111).toString(2)

//'0'

((('🀄'.codePointAt(0) >> 18) & 0b00000111) | 0b11110000).toString(2)

//'11110000'

((('🀄'.codePointAt(0) >> 18) & 0b00000111) | 0b11110000).toString(16)

//'f0'

結果

code:js

[

((('🀄'.codePointAt(0) >> 18) & 0b00000111) | 0b11110000),

((('🀄'.codePointAt(0) >> 12) & 0b00111111) | 0b10000000),

((('🀄'.codePointAt(0) >> 6) & 0b00111111) | 0b10000000),

(('🀄'.codePointAt(0) & 0b00111111) | 0b10000000)

]

ほっけ

code:js

'𩸽'.codePointAt(0).toString(2)

// '101001111000111101'

// 0b10_1001_1110_0011_1101

'𩸽'.codePointAt(0)

// 171581

'𩸽'.codePointAt(0).toString(16)

// '29e3d'

[

('𩸽'.codePointAt(0) & 0b0001_1100_0000_0000_0000_0000) >> 18 | 0b1111_0000,

('𩸽'.codePointAt(0) & 0b0000_0011_1111_0000_0000_0000) >> 12 | 0b1000_0000,

('𩸽'.codePointAt(0) & 0b0000_0000_0000_1111_1100_0000 ) >> 6 | 0b1000_0000,

('𩸽'.codePointAt(0) & 0b0000_0000_0000_0000_0011_1111 ) | 0b1000_0000

]

code:1

0b0000_0010_1001_1110_0011_1101 ... 171581 (0x029e3d)

& 0b0001_1100_0000_0000_0000_0000 ... 1835008(0x1c0000)との論理積をとる

---------------------------------

0b0000_0000_0000_0000_0000_0000 ... 0(0x00)

> 18 ... 18ビット右にシフトする

---------------------------------

0b0000_0000 ... 0 (0x00)

| 0b1111_0000 ... 240(0xf0)との論理和をとる

---------------------------------

0b1111_0000 ... 240(0xf0)

code:2

0b0000_0010_1001_1110_0011_1101 ... 171581(0x29e3d)

& 0b0000_0011_1111_0000_0000_0000 ... 258048(0x3f000)との論理積をとる

---------------------------------

0b0000_0010_1001_0000_0000_0000 ... 167936(0x29000)

> 12 ... 12ビット右にシフトする

---------------------------------

0b0010_1001 ... 41 (0x29)

| 0b1000_0000 ... 128(0x80)との論理和をとる

---------------------------------

0b1010_1001 ... 169(0xa9)

code:3

0b0000_0010_1001_1110_0011_1101 ... 171581(0x29e3d)

& 0b0000_0000_0000_1111_1100_0000 ... 4032 (0x00fc0)との論理積をとる

---------------------------------

0b0000_0000_0000_1110_0000_0000 ... 3584(0xe00)

> 6 ... 6ビット右にシフトする

---------------------------------

0b0011_1000 ... 56 (0x38)

| 0b1000_0000 ... 128(0x80)との論理和をとる

---------------------------------

0b1011_1000 ... 184(0xb8)

code:4

0b0000_0010_1001_1110_0011_1101 ... 171581(0x29e3d)

& 0b0000_0000_0000_0000_0011_1111 ... 63 (0x0003f)との論理積をとる

---------------------------------

0b0011_1101 ... 61 (0x3d) ※ シフトはしない

| 0b1000_0000 ... 128(0x80)との論理和をとる

---------------------------------

0b1011_1101 ... 189(0xbd)