Differences between cstring and string and their conversion

When using MFC for programming, the string obtained by using getwindowtext in the dialog box is of the cstring type, and the cstring belongs to the MFC class. Some Standard C/C ++ library functions cannot directly operate on the cstring type, so we often encounter the situation of converting the cstring type to char * and other data types. Here is a summary!

First of all, it should be clear that there is no string type in Standard C, and string is a class for Standard C ++ to expand string operations. However, we know that the header file string. H is included in standard C. It should be distinguished here. This string is not another string.The string. h header file defines some of the frequently used string operation functions, such as strcpy, strcat, and strcmp. However, the operation objects of these functions are strings pointed to by char. The string operation object of C ++ is a string type string. This class reinstalls some operators and adds some string operation member functions to make the operation string more convenient. Sometimes we need to use the string and char * strings together, so the conversion of these two types will also be involved.

1. cstringAnd String Conversion

 String STR = "  Ksarea  " ;
Cstring CSTR (Str. c_str ()); // Or cstring CSTR (Str. Data (); during initialization  
 CSTR = Str. c_str (); //  Or CSTR = Str. Data ();  
 STR = CSTR. getbuffer ( 0 ); //  Cstring-> string  
 CSTR. Format ( "  % S  " , Str. c_str ()); // String-> cstring  
 CSTR. Format ( "  % S  " , Str. Data ()); //  String-> cstring  
 STR = lpcstr (CSTR ); //  Cstring-> string 

/*The difference between c_str () and data () is that the former returns a string with '\ 0', and the latter returns a string without' \ 0 '.*/

2. cstringAnd int Conversion

IntI =123;
Cstring STR;
Str. Format ("% D", I );//INT-> other basic types of cstring conversion are similar.
I = atoi (STR );//Cstring-> int and (atof, ATOL)
 

3. char *And cstring Conversion

Cstring CSTR ="Ksarea";
Char* Ptemp = CSTR. getbuffer (0);
Char* STR;
Strcpy (STR, ptemp );//Cstring-> char *
CSTR. releasebuffer (-1);
Char* STR ="Lovesha";
Cstring CSTR = STR;//Char *-> cstring type cannot be directly assigned to cstring
 

The conversion between int, float, string, and char * can be forced conversion, or the standard library function.

There are many conversion methods for cstring and other types, but they all share the same path. In the same direction, the type is first converted to char *, because char * is a bridge between different types.
To obtain the char * type, it is very easy to convert it to another type.
C ++ standard is used to discard char * stringsProgramThe string class in the library, because it is compared with the former, does not have to worry about whether the memory is sufficient, string length, and so on, and as a class, the integrated operation functions are sufficient to meet our needs in most cases (or even 100%. We can use = to assign values, = to compare, + to concatenate and so on. We can think of it as the basic data type of C ++.

[Thank you for your reference]
Http://blog.csdn.net/bitxinhai/archive/2008/04/14/2292014.aspx

[Other]
1. header file of string: <iostream>, <string>, using namespace STD;
2. cstring header file: <afx. h>