CString and string

CString and string
(i) overview

String and CString are string template classes, string classes defined by the Standard template class (STL), are included in the C + + standard;

CString (typedef CStringT > CString) is the most commonly used string class in Visual C + + and inherits from the CSimpleStringT class, mainly used in MFC and ATL programming, with char (applied to ANSI) for main data types , wchar_t (Unicode), TCHAR (ANSI and Unicode are available);

Char* is the most commonly used string pointer in C programming, and generally takes '/' as the end sign;

(ii) Construction

The string is convenient and can be constructed from almost all strings, including CString and char*;

CString second, can be constructed from some basic string variables, including char* and so on;

Char* does not have a constructor, only can be assigned value;

Example:

char* psz = "Joise";

CString CStr (PSZ);

String str (CSTR);

(c) Operator overloading

A) operator=

String is the most convenient and can be used to assign values to almost all strings, including CString and char*;

CString second, can directly use some basic string assignment, including char* and so on;

Char* can only be assigned by pointers, and is extremely dangerous operation, it is recommended to use strcpy or memcpy, and char* at the time of declaration, if the initial value is not assigned to the proposed first set to NULL, to avoid wild pointers, so you are 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, can be directly with the char* to add, but can not use the + operator, that is, string str = str + CSTR is illegal, must be converted to char*;

Char* does not have a + operation, can only use strcat to connect two pointers together;

Example:

char* psz = "Joise";

CString CStr = psz;

CStr = CStr + psz;

string str = Psz;

str = str + str + psz;

strcat (Psz, psz);

strcat (Psz, CStr);//Legal

strcat (Psz, str);//Illegal, this shows that CString can be automatically converted to a const char*, and string does not

c) operator + =

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

CString second, can be compared with some basic string variables + =, including char*, etc.;

Char* does not have the + = operator and can only use strcat to connect two pointers together;

d) operator[]

CString is best when an assertion exception is thrown when crossing the bounds;

String and char* subscript out-of-bounds results not defined;

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 can not be compared, but can be compared with char*, and the comparison is the value, not the address;

cout << (Psz = = CStr);

cout << (psz = = str);

cout << (str = = Psz);

cout << (CStr = = psz);//The above code return is 1

(iv) Common algorithms

A) Find

function char* String CString
Finds the specified value STRCHR
Strstr
Strrstr
Strspn Find Find
The first matching value fild_first_of findoneof from the back to find Reservefind specify the matching method find_if
Note: In find_if, the values in the range are put into the matching function until True

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 find the specified value (case insensitive) _stricmp
_strnicmp
_stricoll
_strnicoll Collatenocase

Comparenocas
Note: The return value if <0 is lower than the value that follows, 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 Find the specified value insert insert
e) Add action char* string CString Dynamic add value strcat push

Append Append

Appendchar

AppendFormat

f) Interception

function char* string CString get partial value with subscript operation Substr left

Mid

Right

Truncate

g) Remove

function char* string CString Remove the partial value remove remove removes the blank value removeblanks

Note: This is provided for ATL, non-C function remove_if Trim

Trimleft

Trimrig

h) Convert case

function char* string CString conversion case _STRLWR

_STRUPR Makelower

Makeupper

i) and other types of conversions

function char* string CString into a digital atoi

Atod

Convert atof Format to char* c_str
GetBuffer

Getbuffersetlen
j) Formatting

Action char* string CString formatting sprintf format

k) Get length

function char* String CString
Get the length of strlen length getlength get the size getalloclength
L) judged to be empty

function char* string CString to determine whether the null is ==null or whether the first character is ' \ s ' Empty IsEmpty
m) Redefine size

function char* string CString redefine size realloc
New Resize GetBufferSetLength
N) Releasing Resources

function char* string CString free

Delete (delete[]) ReleaseBuffer

Releasebuffersetlength

(v) Safety >

CString > String > char*;

(vi) Flexibility

CString > String >char*;

(vii) Portability

char* = string > CString

CString and string