Conversion between cstring, wchar_t, Int, String, char * of VC

Cstring to wchar_t

Cstring Path = "ASDF ";

Wchar_t wstr [1, 256] = path. allocsysstring ();

Or:

Wchar_t wcstring [256];

Multibytetowidechar (cp_acp, 0, path,-1, wcstring, 256 );

Wchar_t to cstring

Widechartomultibyte (cp_acp, 0, wcstring, 256,

Path. getbuffer (0), 256, null, null );

Path. releasebuffer (0 );

 

String to cstring
Cstring. Format ("% s", String. c_str ());

Convert Char to cstring
Cstring. Format ("% s", char *);

Char to string
String S (char *);

String to char *
Char * P = string. c_str ();

Cstring to string
String S (cstring. getbuffer ());

Cstring STR = "fdjfdas ";
String S = (lpctstr) STR;

1, string-> cstring
Cstring. Format ("% s", String. c_str ());
C_str () is indeed better than data.
2, char-> string
String S (char *);
You can only initialize it. It is best to use assign () unless it is initialized ().
3, cstring-> string
String S (cstring. getbuffer ());
Releasebuffer () is required after getbuffer (). Otherwise, no space occupied by the buffer is released.

As mentioned in C ++ standard function library
There are three functions that can convert the content of a string to a character array and a C-string
1. Data (), returns a string array without "/0"
2, c_str (), returns a string array with "/0"
3, copy ()

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Conversion between cstring, Int, char *, and char [100 --

Conversion between cstring, Int, char *, and char [100 --

Cstring mutual int Conversion

Converts a character to an integer. You can use atoi, _ atoi64, or atol.
To convert a number to a cstring variable, you can use the format function of cstring. For example
Cstring S;
Int I = 64;
S. Format ("% d", I)
The format function is very powerful and worth your research.

Void cstrdlg: onbutton1 ()
{
// Todo: add your control notification handler code here
Cstring Ss = "1212.12 ";
Int temp = atoi (char *) lpctstr (SS ));

Cstring AA;
AA. Format ("% d", temp );
Afxmessagebox ("Var is" + AA );
}

Sart. Format ("% s", Buf );

Convert cstring to char *

/// Char * To cstring
Cstring strtest;
Char * charpoint;
Charpoint = "give string a value ";
Strtest = charpoint;

/// Cstring to char *
Charpoint = strtest. getbuffer (strtest. getlength ());

There is no string in Standard C, char * = char [] = string

 

Char * To cstring

You can use the cstring. Format ("% s", char *) method to convert char * To cstring.

Convert cstring to char *

Use the operator (lpcstr) strtest or (char *) (lpcstr) strtest.

Cstring conversion char [100]

Char A [100];
Cstring STR ("aaaaaa ");
Strncpy (A, (lpctstr) STR, sizeof ());

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(1) Overview

String and cstring are both string template classes. string is a string class defined by the standard template class (STL) and has been incorporated into the C ++ standard;

Cstring (typedef cstringt> cstring) is the most common string class in Visual C ++. It inherits from the csimplestringt class and is mainly used in MFC and ATL programming, the main data types include char (used in ANSI), wchar_t (UNICODE), and tchar (both ANSI and Unicode );

Char * is the most commonly used string pointer in C programming. It generally ends with '/0;

(2) Construction

String is convenient and can be constructed from almost all strings, including cstring and char *;

Followed by cstring, which can be constructed from some basic string variables, including char;

Char * has no constructor and can only be assigned a value;

Example:

Char * psz = "joise ";

Cstring CSTR (psz );

String STR (CSTR );

(3) Operator Overloading

A) operator =

String is the most convenient, and almost all strings can be assigned directly, including cstring and char *;

Followed by cstring. You can directly assign values using some basic strings, including char;

Char * can only be assigned values by pointers, which is extremely dangerous. We recommend that you use strcpy or memcpy. In addition, if the initial value is not assigned to char *, we recommend that you set it to null first, to avoid wild pointers and drive you crazy;

Example:

Char * psz = NULL;

Psz = new char [10]; // Of course, the above is directly written as char * psz = new char [10 ];

Memset (psz, 0, 10 );

Strcpy (psz, "joise ");

Cstring CSTR;

CSTR = psz;

String STR;

STR = psz;

STR = CSTR;

Delete [] psz;

B) operator +

String is similar to cstring. It can be added directly to char *, but the + operator cannot be used with each other. That is, string STR = STR + CSTR is invalid and must be converted to char *;

Char * has no + operation. Only two pointers can be connected using strcat;

Example:

Char * psz = "joise ";

Cstring CSTR = psz;

CSTR = CSTR + psz;

String STR = psz;

STR = STR + psz;

Strcat (psz, psz );

Strcat (psz, CSTR); // valid

Strcat (psz, STR); // invalid. Therefore, cstring can be automatically converted to const char *, but string cannot.

C) operator ++ =

String is the most powerful and can be used with almost all string variables + =, including cstring and char *;

Followed by cstring, which can be + = with some basic string variables, including char;

Char * has no + = Operator and can only use strcat to connect two pointers;

D) operator []

The cstring is the best. When a cross-border request is made, an asserted exception is thrown;

The results of the out-of-bounds string and char * subscripts are undefined;

Example:

Char * psz = "joise ";

Cstring CSTR = psz;

Cout <CSTR [8];

String STR = psz;

Cout <STR [8];

Cout <psz [8];

E) operator =, Operator! =, Operator>, operator <, operator> =, perator <=

Cstring and string cannot be compared, but both can be compared with char * and compared with the value rather than the address;

Cout <(psz = CSTR );

Cout <(psz = Str );

Cout <(STR = psz );

Cout <(CSTR = psz); // The code above returns 1

(4) common algorithms

A) Search

Char * string cstring
Find the specified strchr
Strstr
Strrstr
Strspfind find
The first matched value fild_first_of findoneof starts from the end to find reservefind. The specified matching method is find_if.

Note: In find_if, values in the range are substituted into the matching function one by one until true is returned.

B) Comparison

Function char * string cstring to find the specified value (case sensitive) strcmp
Strncmp
Strcoll
_ Strncoll operator <
Operator>
Operator <=
Operator> =
Operator =
Operator! = Collate

Compare searches for the specified value (Case Insensitive) _ stricmp
_ Strnicmp
_ Stricoll
_ Strnicoll collatenocase

Comparenocas

Note: If the return value is <0, the previous value is smaller than the subsequent value, and vice versa.

C) replace

Function char * string cstring to find the specified value _ strset
_ Strnset
Replace
Replace_copy
Replace_copy_if
Replace_if replace

D) insert

Function char * string cstring to find the specified value insert

E) added the dynamic added value of char * string cstring strcat push.

Append append

Appendchar

Appendformat

F) intercept

Function char * string cstring get part value substr left

Mid

Right

Truncate

G) Remove

Function char * string cstring remove part of the value remove Blank Value removeblks

Note: This is provided by ATL. Non-C function remove_if trim

Trimleft

Trimrig

H) case-insensitive Conversion

Function: Convert char * string cstring to uppercase/lowercase _ strlwr

_ Strupr makelower

Makeupper

I) conversion from other types

Convert char * string cstring to a number atoi

Atod

Convert atof format to char * c_str
Getbuffer

Getbuffersetlen

J) Format

Function char * string cstring formatting sprintf format

K) Get the length

Char * string cstring
Get strlen length getlength get size getalloclength

L) null judgment

Function char * string cstring determines whether it is null to determine whether = NULL or whether the first character is '/0' empty isempty

M) redefinition size

Function char * string cstring redefinition realloc
New resize getbuffersetlength

N) release resources

Function char * string cstring releases free

Delete (Delete []) releasebuffer

Releasebuffersetlength

(5) Security>

Cstring> string> char *;

(6) Flexibility

Cstring> string> char *;

(7) portability

Char * = string> cstring