Type conversion in C ++, static_cast, reinterpret_cast, boost: lexical_cast

In short, static_cast <> will try to convert, for example, float-to-integer, while reinterpret_cast <> simply changes the compiler's intention to reconsider that object as another type.

 

Float F = 123.4;
Int I = (INT) F; // correct
Int J = static_cast <int> (f); // correct
Int J = boost: lexical_cast <int> (f); // Error
Int J = boost: lexical_cast <int> (F * 10); // correct

 

Char ch [4] = "123 ";
Int BDL = static_cast <int> (CH [2]); // correct 51 (3 ASCII code): convert to the corresponding ASCII code
Int bjl = boost: lexical_cast <int> (CH [2]); // correct 3
Int bd1 = static_cast <int> (CH); // compilation error, cannot be converted like this
Int bj1 = boost: lexical_cast <int> (CH); // 123

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Static_cast:

ALRA: tcpmsg * ptcpmsg = (ALRA: tcpmsg *) wparam;

Float to integer
Pttopleft. Y = static_cast <int> (RDBMS. Height () * (1.0/5 ));

Converts a byte to an unsigned byte.
Assert (0x0f = static_cast <byte> (pdata [2]);

Static_cast <unsigned int> (static_cast <unsigned char> (iocem. szdata [I])

Retrieve the integer from the parameter:
Int ncommandid = static_cast <int> (wparam );

Convert an integer to a parameter type:
Static_cast <lparam> (ncommandid)
Static_cast <uint> (ncommandid)

Static_cast <wparam> (makeword (nmorsfibler, ncommroute), static_cast <lparam> (makewparam (nrorsport, makeword (nnewstaus, noldstaus ))

 

Get the class pointer and convert it to the specified class:
Cpagedeviceboxiopm * pparent = static_cast <cpagedeviceboxiopm *> (getparent ());
Return static_cast <cdocdevice *> (static_cast <cformdevice *> (pparent)-> getdocument ());

Transfer pointer type:
Afxbeginthread (alracommit: sendthread, static_cast <lpvoid> (pparam ));
ALRA: psendingthreadparam pparam = static_cast <ALRA: psendingthreadparam> (lparam );

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Reinterpret_cast:

Unsigned char * P = reinterpret_cast <unsigned char *> (pdata + 5 );

Passing message pointer parameters:
Postmessage (ALRA: um_send_a_package, reinterpret_cast <wparam> (pcardparam), 0 );
ALRA: psendingthreadparam pcardparam = reinterpret_cast <ALRA: psendingthreadparam> (wparam );

Convert a reference to a specific type:
ALRA: iocem & iocem = reinterpret_cast <ALRA: iocem &> (rpackage );
ALRA: iopm & iopm = reinterpret_cast <ALRA: iopm &> (rpackage );

Ret =: sqlprepare (hstmt, reinterpret_cast <uchar *> (strsql. getbuffer (0), SQL _nt );

Getparent ()-> postmessage (ALRA: um_device_card_selection_change,
Static_cast <wparam> (getdlgctrlid (), // pass the integer
Reinterpret_cast <lparam> (pcard); // pass pointer type

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Boost: lexical_cast:

Convert the bytes type to the int type, and then convert it to the byte type. For example, vs [3] = '2' is converted to int 2, and then to byte, Which is ox02 0000 0010.
Makeword (static_cast <byte> (boost: lexical_cast <int> (vs [3]), static_cast <byte> (boost :: lexical_cast <int> (vs [2])
Convert string to double:
Boost: lexical_cast <double> (strvalue );
Convert the cstring variable associated with the Edit Control to the double type:
Boost: lexical_cast <double> (m_strmrlimit2.getbuffer ());

When there are no decimal places after X 10 in the following two items, the effect is the same. If there are decimal places, lexical_cast <int> will fail.
Iopm. nswitchlimit = static_cast <int> (boost: lexical_cast <double> (m_strsrswitchthreshold.getbuffer () * 10.0 );
Iocem. nchanged = boost: lexical_cast <int> (boost: lexical_cast <float> (this-> m_strchanged) * 10 );

STD: String S = lexical_cast <STD: String> (123456.7); // convert the floating point type to the string type.