casting int to char using C style casting

Question

In traditional C you can do   int i   48  char c    char i    Now c holds the value of 48      Of course if i  gt  255 then c will not hold the same value as i       Which of the c   casting methods  static cast  reinterpret cast  is suited for getting this job done

User · Answer

You should use static cast lt char gt  i  to cast the integer i to char   reinterpret cast should almost never be used  unless you want to cast one type into a fundamentally different type   Also reinterpret cast is machine dependent so safely using it requires complete understanding of the types as well as how the compiler implements the cast   For more information about C   casting see    When should static cast  dynamic cast  const cast and reinterpret cast be used  http   www cplusplus com doc tutorial typecasting

User · Answer

Using static cast would probably result in something like this      This does not prevent a possible type overflow const char char max   -1   int i   48  char c    i  amp  char max     To prevent possible type overflow you could do this   const char char max    char    unsigned char  char -1     2    int i   128  char c    i  amp  char max      Would always result in positive signed values    Where reinterpret cast would probably just directly convert to char  without any cast safety  -  Never use reinterpret cast if you can also use static cast  If you re casting between classes  static cast will also ensure  that the two types are matching  the object is a derivate of the cast type    If your object a polymorphic type and you don t know which one it is  you should use dynamic cast which will perform a type check at runtime and return nullptr if the types do not match   IF you need const cast you most likely did something wrong and should think about possible alternatives to fix const correctness in your code

User · Answer

reinterpret cast cannot be used for this conversion  the code will not compile  According to C  03 standard section 5 2 10-1   Conversions that can be performed explicitly using reinterpret cast are listed below  No other conversion can be performed explicitly using reinterpret cast   This conversion is not listed in that section  Even this is invalid   long l   reinterpret cast lt long gt  i    static cast is the one which has to be used here  See this and this SO questions

User · Answer

You can implicitly convert between numerical types  even when that loses precision   char c   i    However  you might like to enable compiler warnings to avoid potentially lossy conversions like this  If you do  then use static cast for the conversion   Of the other casts    dynamic cast only works for pointers or references to polymorphic class types  const cast can t change types  only const or volatile qualifiers  reinterpret cast is for special circumstances  converting between pointers or references and completely unrelated types  Specifically  it won t do numeric conversions  C-style and function-style casts do whatever combination of static cast  const cast and reinterpret cast is needed to get the job done

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