C :: 다양한 형변환

[출처] 다양한 형변환|작성자 삼돌이

Environment: Compiled using VC6.0 Sp3 and tested using Win95/98 WinNT4.0 and Win 2000
Here are a few data Conversions with small examples :-



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PART ONE :- DECIMAL CONVERSIONS
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Decimal To Hexa :-
Use _itoa( ) function and set radix to 16.

char hexstring[10];
int number = 30;
itoa( number, hexstring, 16);



In hexstring is 1e.

Hexa To Decimal :-
a)You can use strtol function and you can specify base.

char * hexstring= "ABCDEF";
char * p;
int number = strtol(hexstring, &p,16);



b) Or you can use this too

bool HexToDecimal (char* HexNumber, int& Number)
{
char* pStopString;
Number = strtol (HexNumber, &pStopString, 16);
return (bool)(Number != LONG_MAX);
}



Decimal to Time :-

char *DecToTime(float fTime, char *szTime)
{
int nHrs, nMin, nSec;
fTime *= 3600;
nHrs = (int)fTime / 3600;
nMin = (int)(fTime - nHrs * 3600) / 60;
nSec = (int)(fTime - nHrs * 3600 - nMin * 60);
wsprintf(szTime, "%02d.%02d.%02d Hrs.Min.Sec.", nHrs, nMin, nSec);
return szTime;
}



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PART TWO :- STRING CONVERSIONS

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String to Hexa :-

sscanf(string, %04X, &your_word16);
// where string = your string and 04 = length of your string and X = hex


Hex to CString :-
CString Str;
unsigned char Write_Buff[1];
Write_Buff[0] = 0x01;
Str.Format("0x0%x",Write_Buff[0]);


COleVariant to CString :-
CString strTemp;
COleVariant Var;
Var = "FirstName";
strTemp = Var.bstrVal;
AfxMessageBox(strTemp);


CString to Char Pointer :-
a) CString MyString = "ABCDEF";
char * szMyString = (char *) (LPCTSTR) MyString;



b) char *pBuffer = new char[1024];
CString strBuf = "Test";
pBuffer = strBuf.GetBuffer(sizeof(pBuffer));



Char Pointer to CString :-
char * mystring = "12345";
CString string = mystring;


Double to CString including the fractional part :-
CString strValue,strInt, strDecimal;
int decimal,sign;
double dValue = 4.125;
strValue = _fcvt(dValue,6,&decimal,&sign);

// Now decimal contains 1 because there is only one digit before the .

strInt = strValue.Left(decimal); // strInt contains 4
strDecimal = strValue.Mid(decimal); // strDecimal contains 125

CString strFinalVal;
strFinalVal.Format("%s.%s",strInt,strDecimal); // strFinalVal contains 4.125



Double To CString :-
CString strValue;
int decimal,sign;

double dValue = 123456789101112;
strValue = _ecvt(dValue,15,&decimal,&sign);


CString To Double :-
strValue = "121110987654321";
dValue = atof(strValue);


CString to LPCSTR :-
CString str1 = _T("My String");
int nLen = str1.GetLength();
LPCSTR lpszBuf = str1.GetBuffer(nLen);
// here do something with lpszBuf...........
str1.ReleaseBuffer();


CString to LPSTR :-
CString str = _T("My String");
int nLen = str.GetLength();
LPTSTR lpszBuf = str.GetBuffer(nLen);
// here do something with lpszBuf...........
str.ReleaseBuffer();

CString to WCHAR* :-
CString str = "A string here" ;
LPWSTR lpszW = new WCHAR[255];

LPTSTR lpStr = str.GetBuffer( str.GetLength() );
int nLen = MultiByteToWideChar(CP_ACP, 0,lpStr, -1, NULL, NULL);
MultiByteToWideChar(CP_ACP, 0, lpStr, -1, lpszW, nLen);
AFunctionUsesWCHAR( lpszW );
delete[] lpszW;



LPTSTR to LPWSTR :-
int nLen = MultiByteToWideChar(CP_ACP, 0, lptStr, -1, NULL, NULL);
MultiByteToWideChar(CP_ACP, 0, lptStr, -1, lpwStr, nLen);



string to LPCTSTR :-

std::string strTemp;

LPCTSTR lpName = strTemp.c_str();


string to BSTR :-
string ss = "Girish";
BSTR _bstr_home = A2BSTR(ss.c_str());


CString to BSTR :-
CString str = "whatever" ;
BSTR resultsString = str.AllocSysString();


_bstr_t to CString :-

#include
#include
_bstr_t bsText("Hai Bayram");
CString strName;
W2A(bsText, strName.GetBuffer(256), 256);
strName.ReleaseBuffer();
AfxMessageBox(strName);

char szFileName[256];
GetModuleFileName(NULL,szFileName,256);
AfxMessageBox(szFileName);



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PART THREE :- CHARACTER ARRAYS

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Char array to integer
char MyArray[20];
int nValue;

nValue = atoi(MyArray);



Char array to float
char MyArray[20];
float fValue;

fValue = atof(MyArray);


Char Pointer to double :-
char *str = " -343.23 ";
double dVal;
dVal = atof( str );


Char Pointer to integer :-
char *str = " -343.23 ";
int iVal;
iVal = atoi( str );



Char Pointer to long :-
char *str = "99999";
long lVal;
lVal = atol( str );


Char* to BSTR :-
char * p = "whatever";
_bstr_t bstr = p;

Float to WORD and Vice Versa :-
float fVar;
WORD wVar;
fVar = 247.346;
wVar = (WORD)fVar; //Converting from float to WORD. The value in wVar would be 247
wVar = 247;
fVar = (float)fVar; //Converting from WORD to float. The value in fVar would be 247.0