What is the difference between (type)value and type(value)?

by

There is no difference; per the standard (§5.2.3):

A simple-type-specifier (7.1.5) followed by a parenthesized expression-list constructs a value of the specified type given the expression list. If the expression list is a single expression, the type conversion expression is equivalent (in definedness, and if defined in meaning) to the corresponding cast expression (5.4).

Since the question specified the difference between type(value) and (type)value, there is absolutely no difference.

If and only if you’re dealing with a comma-separated list of values can there be a difference. In this case:

If the expression list specifies more than a single value, the type shall be a class with a suitably declared constructor (8.5, 12.1), and the expression T(x1, x2, …) is equivalent in effect to the declaration T t(x1, x2, …); for some invented temporary variable t, with the result being the value of t as an rvalue.

As Troubadour pointed out, there are a certain names of types for which the type(value) version simply won’t compile. For example:

char *a = (char *)string;

will compile, but:

char *a = char *(string);

will not. The same type with a different name (e.g., created with a typedef) can work though:

typedef char *char_ptr;

char *a = char_ptr(string);

More Related Contents:

  1. Why it is so ? And It is without you explicitly do casting [duplicate]
  2. Why use static_cast(x) instead of (int)x?
  3. What happens if I assign a negative value to an unsigned variable?
  4. Is const_cast safe?
  5. What is the difference between static_cast and C style casting?
  6. How to output a character as an integer through cout?
  7. How is a variable at the same address producing 2 different values? [duplicate]
  8. How to convert string to char array in C++?
  9. Conversion constructor vs. conversion operator: precedence
  10. Implicit type conversion with template
  11. Modifying a const through a non-const pointer
  12. Efficient unsigned-to-signed cast avoiding implementation-defined behavior
  13. Why unsigned int 0xFFFFFFFF is equal to int -1?
  14. error: cast from ‘void*’ to ‘int’ loses precision
  15. What is the difference between C-like casting and functional casting? [duplicate]
  16. Why is “operator void” not invoked with cast syntax?
  17. What is the difference between casting and conversion? [duplicate]
  18. C++ class member function pointer to function pointer
  19. Convert float to std::string in C++
  20. Multiple implicit conversions on custom types not allowed?
  21. std::lexical_cast – is there such a thing?
  22. C++ floating point to integer type conversions
  23. Does one double promote every int in the equation to double?
  24. Handling overflow when casting doubles to integers in C
  25. Fastest way to Convert String to Binary?
  26. Is casting std::pair const& to std::pair const& safe?
  27. How can CString be passed to format string %s?
  28. C++ Implicit Conversion (Signed + Unsigned)
  29. non-const pointer argument to a const double pointer parameter
  30. What is the modern, correct way to do type punning in C++?

Leave a Comment