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6

I am trying to write a generic function which takes input as uint8, uint16, uint32, uint64, .... and return the maximum value with datatype of largest element?

For example:

template < typename T, typename X>
auto Max_Number ( T valueA, X valueB )
 if ( valueA > valueB ) 
 return valueA;
else
 return valueB;

P.S: this example assumes the largest element is of largest datatype.

c++ c++11 templates return-type decltype

share|improve this question

edited 12 hours ago

Oblivion

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• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  take a look at std::variant That's probably the closest since C++ is strongly typed
  
  – doug
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  There might be some template wizards that could suggest something, but I'm fairly certain that the return type must be fixed
  
  – selbie
  12 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  Have you tried to use plain std::max? Remember that integer types can safely be implicitly converted to a larger type.
  
  – Some programmer dude
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Someprogrammerdude Yep, that should work given his example's statement that the largest arg magnitude is also the largest datatype applies in all other cases.
  
  – doug
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Are the arguments always unsigned? It's not clear because of that "...". If they are, I would use simply uintmax_t Max_Number(uintmax_t a, uintmax_t b) ....
  
  – Daniel Langr
  11 hours ago
  
  

  
  
  
  

add a comment
 | 

6

I am trying to write a generic function which takes input as uint8, uint16, uint32, uint64, .... and return the maximum value with datatype of largest element?

For example:

template < typename T, typename X>
auto Max_Number ( T valueA, X valueB )
 if ( valueA > valueB ) 
 return valueA;
else
 return valueB;

P.S: this example assumes the largest element is of largest datatype.

c++ c++11 templates return-type decltype

share|improve this question

edited 12 hours ago

Oblivion

2,58211 gold badge44 silver badges2121 bronze badges

asked 12 hours ago

Kiran NDKiran ND

3111 bronze badge

New contributor

Kiran ND is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  take a look at std::variant That's probably the closest since C++ is strongly typed
  
  – doug
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  There might be some template wizards that could suggest something, but I'm fairly certain that the return type must be fixed
  
  – selbie
  12 hours ago
  
  

  
  
  
  


• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  Have you tried to use plain std::max? Remember that integer types can safely be implicitly converted to a larger type.
  
  – Some programmer dude
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Someprogrammerdude Yep, that should work given his example's statement that the largest arg magnitude is also the largest datatype applies in all other cases.
  
  – doug
  12 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Are the arguments always unsigned? It's not clear because of that "...". If they are, I would use simply uintmax_t Max_Number(uintmax_t a, uintmax_t b) ....
  
  – Daniel Langr
  11 hours ago
  
  

  
  
  
  

add a comment
 | 

I am trying to write a generic function which takes input as uint8, uint16, uint32, uint64, .... and return the maximum value with datatype of largest element?

For example:

template < typename T, typename X>
auto Max_Number ( T valueA, X valueB )
 if ( valueA > valueB ) 
 return valueA;
else
 return valueB;

P.S: this example assumes the largest element is of largest datatype.

c++ c++11 templates return-type decltype

share|improve this question

edited 12 hours ago

Oblivion

2,58211 gold badge44 silver badges2121 bronze badges

asked 12 hours ago

Kiran NDKiran ND

3111 bronze badge

New contributor

Kiran ND is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

template < typename T, typename X>
auto Max_Number ( T valueA, X valueB )
 if ( valueA > valueB ) 
 return valueA;
else
 return valueB;

share|improve this question

edited 12 hours ago

Oblivion

2,58211 gold badge44 silver badges2121 bronze badges

asked 12 hours ago

Kiran NDKiran ND

3111 bronze badge

New contributor

Kiran ND is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 12 hours ago

Oblivion

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asked 12 hours ago

Kiran NDKiran ND

3111 bronze badge

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Kiran ND is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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edited 12 hours ago

Oblivion

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edited 12 hours ago

Oblivion

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asked 12 hours ago

Kiran NDKiran ND

3111 bronze badge

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Kiran ND is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 12 hours ago

Kiran NDKiran ND

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3 Answers
3

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10

The return type must be determined at compile-time. You might use std::common_type (since C++11):

For arithmetic types not subject to promotion, the common type may be viewed as the type of the (possibly mixed-mode) arithmetic expression such as T0() + T1() + ... + Tn().

template < typename T, typename X>
std::common_type_t<T, X> Max_Number ( T valueA, X valueB ) 
 ...

Or use std::conditional (since C++11) to declare the return type as the big one (whose sizeof is greater).

template < typename T, typename X>
std::conditional_t<sizeof(T) >= sizeof(X), T, X> Max_Number ( T valueA, X valueB ) 
 ...

share|improve this answer

edited 12 hours ago

answered 12 hours ago

songyuanyaosongyuanyao

106k1111 gold badges205205 silver badges275275 bronze badges

add a comment
 | 

6

Here is an example solution with std:: variant

template < typename T, typename X> 
std::variant<T, X> Max_Number ( T valueA, X valueB )

 std::variant<T, X> res;
 if ( valueA > valueB ) 
 res = valueA; 
 else 
 res = valueB; 
 return res;

share|improve this answer

edited 12 hours ago

answered 12 hours ago

OblivionOblivion

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add a comment
 | 

1

The Trailing return with a conditional operator is another way to go, which is available since c++11.

(See online live)

template <typename T, typename X>
constexpr auto Max_Number(T valueA, X valueB)-> decltype(valueA > valueB ? valueA : valueB)

 return valueA > valueB ? valueA : valueB;

---

See some advantages of using trailing return type here: Advantage of using trailing return type in C++11 functions

share|improve this answer

answered 39 mins ago

JeJoJeJo

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10

The return type must be determined at compile-time. You might use std::common_type (since C++11):

For arithmetic types not subject to promotion, the common type may be viewed as the type of the (possibly mixed-mode) arithmetic expression such as T0() + T1() + ... + Tn().

template < typename T, typename X>
std::common_type_t<T, X> Max_Number ( T valueA, X valueB ) 
 ...

Or use std::conditional (since C++11) to declare the return type as the big one (whose sizeof is greater).

template < typename T, typename X>
std::conditional_t<sizeof(T) >= sizeof(X), T, X> Max_Number ( T valueA, X valueB ) 
 ...

share|improve this answer

edited 12 hours ago

answered 12 hours ago

songyuanyaosongyuanyao

106k1111 gold badges205205 silver badges275275 bronze badges

add a comment
 | 

10

The return type must be determined at compile-time. You might use std::common_type (since C++11):

For arithmetic types not subject to promotion, the common type may be viewed as the type of the (possibly mixed-mode) arithmetic expression such as T0() + T1() + ... + Tn().

template < typename T, typename X>
std::common_type_t<T, X> Max_Number ( T valueA, X valueB ) 
 ...

Or use std::conditional (since C++11) to declare the return type as the big one (whose sizeof is greater).

template < typename T, typename X>
std::conditional_t<sizeof(T) >= sizeof(X), T, X> Max_Number ( T valueA, X valueB ) 
 ...

share|improve this answer

edited 12 hours ago

answered 12 hours ago

songyuanyaosongyuanyao

106k1111 gold badges205205 silver badges275275 bronze badges

add a comment
 | 

The return type must be determined at compile-time. You might use std::common_type (since C++11):

For arithmetic types not subject to promotion, the common type may be viewed as the type of the (possibly mixed-mode) arithmetic expression such as T0() + T1() + ... + Tn().

template < typename T, typename X>
std::common_type_t<T, X> Max_Number ( T valueA, X valueB ) 
 ...

Or use std::conditional (since C++11) to declare the return type as the big one (whose sizeof is greater).

template < typename T, typename X>
std::conditional_t<sizeof(T) >= sizeof(X), T, X> Max_Number ( T valueA, X valueB ) 
 ...

share|improve this answer

edited 12 hours ago

answered 12 hours ago

songyuanyaosongyuanyao

106k1111 gold badges205205 silver badges275275 bronze badges

template < typename T, typename X>
std::common_type_t<T, X> Max_Number ( T valueA, X valueB ) 
 ...

template < typename T, typename X>
std::conditional_t<sizeof(T) >= sizeof(X), T, X> Max_Number ( T valueA, X valueB ) 
 ...

share|improve this answer

edited 12 hours ago

answered 12 hours ago

songyuanyaosongyuanyao

106k1111 gold badges205205 silver badges275275 bronze badges

answered 12 hours ago

songyuanyaosongyuanyao

106k1111 gold badges205205 silver badges275275 bronze badges

answered 12 hours ago

songyuanyaosongyuanyao

106k1111 gold badges205205 silver badges275275 bronze badges

6

Here is an example solution with std:: variant

template < typename T, typename X> 
std::variant<T, X> Max_Number ( T valueA, X valueB )

 std::variant<T, X> res;
 if ( valueA > valueB ) 
 res = valueA; 
 else 
 res = valueB; 
 return res;

share|improve this answer

edited 12 hours ago

answered 12 hours ago

OblivionOblivion

2,58211 gold badge44 silver badges2121 bronze badges

add a comment
 | 

6

Here is an example solution with std:: variant

template < typename T, typename X> 
std::variant<T, X> Max_Number ( T valueA, X valueB )

 std::variant<T, X> res;
 if ( valueA > valueB ) 
 res = valueA; 
 else 
 res = valueB; 
 return res;

share|improve this answer

edited 12 hours ago

answered 12 hours ago

OblivionOblivion

2,58211 gold badge44 silver badges2121 bronze badges

add a comment
 | 

Here is an example solution with std:: variant

template < typename T, typename X> 
std::variant<T, X> Max_Number ( T valueA, X valueB )

 std::variant<T, X> res;
 if ( valueA > valueB ) 
 res = valueA; 
 else 
 res = valueB; 
 return res;

share|improve this answer

edited 12 hours ago

answered 12 hours ago

OblivionOblivion

2,58211 gold badge44 silver badges2121 bronze badges

template < typename T, typename X> 
std::variant<T, X> Max_Number ( T valueA, X valueB )

 std::variant<T, X> res;
 if ( valueA > valueB ) 
 res = valueA; 
 else 
 res = valueB; 
 return res;

share|improve this answer

edited 12 hours ago

answered 12 hours ago

OblivionOblivion

2,58211 gold badge44 silver badges2121 bronze badges

answered 12 hours ago

OblivionOblivion

2,58211 gold badge44 silver badges2121 bronze badges

answered 12 hours ago

OblivionOblivion

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1

The Trailing return with a conditional operator is another way to go, which is available since c++11.

(See online live)

template <typename T, typename X>
constexpr auto Max_Number(T valueA, X valueB)-> decltype(valueA > valueB ? valueA : valueB)

 return valueA > valueB ? valueA : valueB;

---

See some advantages of using trailing return type here: Advantage of using trailing return type in C++11 functions

share|improve this answer

answered 39 mins ago

JeJoJeJo

9,84933 gold badges1515 silver badges4545 bronze badges

add a comment
 | 

1

The Trailing return with a conditional operator is another way to go, which is available since c++11.

(See online live)

template <typename T, typename X>
constexpr auto Max_Number(T valueA, X valueB)-> decltype(valueA > valueB ? valueA : valueB)

 return valueA > valueB ? valueA : valueB;

---

See some advantages of using trailing return type here: Advantage of using trailing return type in C++11 functions

share|improve this answer

answered 39 mins ago

JeJoJeJo

9,84933 gold badges1515 silver badges4545 bronze badges

add a comment
 | 

The Trailing return with a conditional operator is another way to go, which is available since c++11.

(See online live)

template <typename T, typename X>
constexpr auto Max_Number(T valueA, X valueB)-> decltype(valueA > valueB ? valueA : valueB)

 return valueA > valueB ? valueA : valueB;

---

See some advantages of using trailing return type here: Advantage of using trailing return type in C++11 functions

share|improve this answer

answered 39 mins ago

JeJoJeJo

9,84933 gold badges1515 silver badges4545 bronze badges

template <typename T, typename X>
constexpr auto Max_Number(T valueA, X valueB)-> decltype(valueA > valueB ? valueA : valueB)

 return valueA > valueB ? valueA : valueB;

share|improve this answer

answered 39 mins ago

JeJoJeJo

9,84933 gold badges1515 silver badges4545 bronze badges

answered 39 mins ago

JeJoJeJo

9,84933 gold badges1515 silver badges4545 bronze badges

answered 39 mins ago

JeJoJeJo

9,84933 gold badges1515 silver badges4545 bronze badges