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9

1

In the CPP reference documentation,

I noticed for char

The character types are large enough to represent any UTF-8 eight-bit
code unit (since C++14)

and for char8_t

type for UTF-8 character representation, required to be large enough
to represent any UTF-8 code unit (8 bits)

Does that mean both are the same type? Or does char8_t have some other feature?

c++ c++14 c++20

share|improve this question

edited 7 hours ago

Boann

38.6k1313 gold badges9393 silver badges123123 bronze badges

asked 8 hours ago

Pavan ChandakaPavan Chandaka

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• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Well, it's clear from looking that char8_t is an 8 bit type. Also, The signedness of char depends on the compiler and the target platform: the defaults for ARM and PowerPC are typically unsigned, the defaults for x86 and x64 are typically signed. while char8_t is always unsigned.
  
  – Elliott Frisch
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  " or does char8_t has an extra edge?" - what do you mean by that?
  
  – Neil Butterworth
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I mean any other benefits
  
  – Pavan Chandaka
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Rats. I was hoping you meant like the magic sword from The Sword and the Sorcerer.
  
  – user4581301
  7 hours ago
  
  

  
  
  
  

add a comment | 

9

1

In the CPP reference documentation,

I noticed for char

The character types are large enough to represent any UTF-8 eight-bit
code unit (since C++14)

and for char8_t

type for UTF-8 character representation, required to be large enough
to represent any UTF-8 code unit (8 bits)

Does that mean both are the same type? Or does char8_t have some other feature?

c++ c++14 c++20

share|improve this question

edited 7 hours ago

Boann

38.6k1313 gold badges9393 silver badges123123 bronze badges

asked 8 hours ago

Pavan ChandakaPavan Chandaka

5,89733 gold badges1111 silver badges2020 bronze badges

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  Well, it's clear from looking that char8_t is an 8 bit type. Also, The signedness of char depends on the compiler and the target platform: the defaults for ARM and PowerPC are typically unsigned, the defaults for x86 and x64 are typically signed. while char8_t is always unsigned.
  
  – Elliott Frisch
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  " or does char8_t has an extra edge?" - what do you mean by that?
  
  – Neil Butterworth
  8 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I mean any other benefits
  
  – Pavan Chandaka
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Rats. I was hoping you meant like the magic sword from The Sword and the Sorcerer.
  
  – user4581301
  7 hours ago
  
  

  
  
  
  

add a comment | 

In the CPP reference documentation,

I noticed for char

The character types are large enough to represent any UTF-8 eight-bit
code unit (since C++14)

and for char8_t

type for UTF-8 character representation, required to be large enough
to represent any UTF-8 code unit (8 bits)

Does that mean both are the same type? Or does char8_t have some other feature?

c++ c++14 c++20

share|improve this question

edited 7 hours ago

Boann

38.6k1313 gold badges9393 silver badges123123 bronze badges

asked 8 hours ago

Pavan ChandakaPavan Chandaka

5,89733 gold badges1111 silver badges2020 bronze badges

share|improve this question

edited 7 hours ago

Boann

38.6k1313 gold badges9393 silver badges123123 bronze badges

asked 8 hours ago

Pavan ChandakaPavan Chandaka

5,89733 gold badges1111 silver badges2020 bronze badges

share|improve this question

edited 7 hours ago

Boann

38.6k1313 gold badges9393 silver badges123123 bronze badges

asked 8 hours ago

Pavan ChandakaPavan Chandaka

5,89733 gold badges1111 silver badges2020 bronze badges

edited 7 hours ago

Boann

38.6k1313 gold badges9393 silver badges123123 bronze badges

edited 7 hours ago

Boann

38.6k1313 gold badges9393 silver badges123123 bronze badges

asked 8 hours ago

Pavan ChandakaPavan Chandaka

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asked 8 hours ago

Pavan ChandakaPavan Chandaka

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1 Answer
1

active

oldest

votes

15

char8_t is not the same as char. It behaves exactly the same as unsigned char though per [basic.fundamental]/9

Type char8_­t denotes a distinct type whose underlying type is unsigned char. Types char16_­t and char32_­t denote distinct types whose underlying types are uint_­least16_­t and uint_­least32_­t, respectively, in <cstdint>.

^{emphasis mine}

---

Do note that since the standard calls it a distinct type, code like

std::cout << std::is_same_v<unsigned char, char8_t>;

will print 0(false), even though char8_t is implemented as a unsigned char. This is because it is not an alias, but a distinct type.

---

Another thing to note is that char can either be implemented as a signed char or unsigned char. That means it is possible for char to have the same range and representation as char8_t, but they are still separate types. char, signed char, unsigned char, and char8_t are the same size, but they are all distinct types.

share|improve this answer

edited 7 hours ago

answered 8 hours ago

NathanOliverNathanOliver

111k1919 gold badges172172 silver badges251251 bronze badges

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  The bigger the C++ numbers, the more I enjoy simple ol' C...
  
  – Michael Dorgan
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  @MichaelDorgan But 98 is bigger than 17 and 98 was... not so fun to work with ;)
  
  – NathanOliver
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @MichaelDorgan: Isn't the "compatibility" with C which increases complexity? as sign issue of char.
  
  – Jarod42
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  @MichaelDorgan in case you are unaware, C also has char16_t, char32_t and associated char/string literals and manipulation functions. (As well as char, unsigned char, signed char, int8_t and uint8_t of course)
  
  – M.M
  7 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  For some definition of "exactly the same". A key feature of char8_t is that it doesn't alias everything under the sun.
  
  – T.C.
  7 hours ago
  

  
  
  
  

 | 
show 10 more comments

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15

char8_t is not the same as char. It behaves exactly the same as unsigned char though per [basic.fundamental]/9

Type char8_­t denotes a distinct type whose underlying type is unsigned char. Types char16_­t and char32_­t denote distinct types whose underlying types are uint_­least16_­t and uint_­least32_­t, respectively, in <cstdint>.

^{emphasis mine}

---

Do note that since the standard calls it a distinct type, code like

std::cout << std::is_same_v<unsigned char, char8_t>;

will print 0(false), even though char8_t is implemented as a unsigned char. This is because it is not an alias, but a distinct type.

---

Another thing to note is that char can either be implemented as a signed char or unsigned char. That means it is possible for char to have the same range and representation as char8_t, but they are still separate types. char, signed char, unsigned char, and char8_t are the same size, but they are all distinct types.

share|improve this answer

edited 7 hours ago

answered 8 hours ago

NathanOliverNathanOliver

111k1919 gold badges172172 silver badges251251 bronze badges

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  The bigger the C++ numbers, the more I enjoy simple ol' C...
  
  – Michael Dorgan
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  @MichaelDorgan But 98 is bigger than 17 and 98 was... not so fun to work with ;)
  
  – NathanOliver
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @MichaelDorgan: Isn't the "compatibility" with C which increases complexity? as sign issue of char.
  
  – Jarod42
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  @MichaelDorgan in case you are unaware, C also has char16_t, char32_t and associated char/string literals and manipulation functions. (As well as char, unsigned char, signed char, int8_t and uint8_t of course)
  
  – M.M
  7 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  For some definition of "exactly the same". A key feature of char8_t is that it doesn't alias everything under the sun.
  
  – T.C.
  7 hours ago
  

  
  
  
  

 | 
show 10 more comments

15

char8_t is not the same as char. It behaves exactly the same as unsigned char though per [basic.fundamental]/9

Type char8_­t denotes a distinct type whose underlying type is unsigned char. Types char16_­t and char32_­t denote distinct types whose underlying types are uint_­least16_­t and uint_­least32_­t, respectively, in <cstdint>.

^{emphasis mine}

---

Do note that since the standard calls it a distinct type, code like

std::cout << std::is_same_v<unsigned char, char8_t>;

will print 0(false), even though char8_t is implemented as a unsigned char. This is because it is not an alias, but a distinct type.

---

Another thing to note is that char can either be implemented as a signed char or unsigned char. That means it is possible for char to have the same range and representation as char8_t, but they are still separate types. char, signed char, unsigned char, and char8_t are the same size, but they are all distinct types.

share|improve this answer

edited 7 hours ago

answered 8 hours ago

NathanOliverNathanOliver

111k1919 gold badges172172 silver badges251251 bronze badges

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  The bigger the C++ numbers, the more I enjoy simple ol' C...
  
  – Michael Dorgan
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  @MichaelDorgan But 98 is bigger than 17 and 98 was... not so fun to work with ;)
  
  – NathanOliver
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @MichaelDorgan: Isn't the "compatibility" with C which increases complexity? as sign issue of char.
  
  – Jarod42
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  @MichaelDorgan in case you are unaware, C also has char16_t, char32_t and associated char/string literals and manipulation functions. (As well as char, unsigned char, signed char, int8_t and uint8_t of course)
  
  – M.M
  7 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  For some definition of "exactly the same". A key feature of char8_t is that it doesn't alias everything under the sun.
  
  – T.C.
  7 hours ago
  

  
  
  
  

 | 
show 10 more comments

char8_t is not the same as char. It behaves exactly the same as unsigned char though per [basic.fundamental]/9

Type char8_­t denotes a distinct type whose underlying type is unsigned char. Types char16_­t and char32_­t denote distinct types whose underlying types are uint_­least16_­t and uint_­least32_­t, respectively, in <cstdint>.

^{emphasis mine}

---

Do note that since the standard calls it a distinct type, code like

std::cout << std::is_same_v<unsigned char, char8_t>;

will print 0(false), even though char8_t is implemented as a unsigned char. This is because it is not an alias, but a distinct type.

---

Another thing to note is that char can either be implemented as a signed char or unsigned char. That means it is possible for char to have the same range and representation as char8_t, but they are still separate types. char, signed char, unsigned char, and char8_t are the same size, but they are all distinct types.

share|improve this answer

edited 7 hours ago

answered 8 hours ago

NathanOliverNathanOliver

111k1919 gold badges172172 silver badges251251 bronze badges

std::cout << std::is_same_v<unsigned char, char8_t>;

share|improve this answer

edited 7 hours ago

answered 8 hours ago

NathanOliverNathanOliver

111k1919 gold badges172172 silver badges251251 bronze badges

answered 8 hours ago

NathanOliverNathanOliver

111k1919 gold badges172172 silver badges251251 bronze badges

answered 8 hours ago

NathanOliverNathanOliver

111k1919 gold badges172172 silver badges251251 bronze badges