The use of std::string

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in ordinary work often use the string class, I remember the bad use of the time often to go to inquire. In the online excerpt summary, for future inquiries convenient:

constructor of the String class:
String (const char *s);     Initializes a string (int N,char c) with the C string s; Initialize with n characters of C

Character manipulation of the string class:
const char &operator[] (int n) const;
const char &at (int n) const;
Char &operator[] (int n);
char &at (int n);
Operator[] and at () both return the position of the nth character in the current string, but the at function provides a scope check that throws a Out_of_range exception when it crosses the border, and the subscript operator [] does not provide check access.
const char *data () const;//returns a non-null-terminated C-character array
const char *C_STR () const;//returns a null-terminated C string
int copy (char *s, int n, int pos = 0) const;//copies the n characters starting at Pos in the current string to a character array starting with S, returning the number of actual copies

Note: For the processing of object characters in string, there are many existing functions in the Cctype header file, which can be conveniently applied

Character description of String:
int capacity () const; Returns the current capacity (that is, the number of elements in a string that do not have to increase memory)
int max_size () const; Returns the length of the largest string that can be stored in a string object
int size () const; Returns the size of the current string
int length () const; Returns the length of the current string
BOOL empty () const; Whether the current string is empty
void Resize (int len,char c);//Set the current size of the string to Len and fill in the insufficient part with the character C

The input and output operations of the String class: The String class overloaded operator operator>> is used for input, and the same overloaded operator operator<< is used for output operations.
The function getline (IStream &in,string &s) is used to read the string from the input stream in to s, separated by a newline character ' \ n '.

Assignment of String:
String &operator= (const string &s);//assigns the string s to the current string
String &assign (const char *s);//Assigning a value with the C type string s
String &assign (const char *s,int n);//n characters assigned value starting with C string s
String &assign (const string &s);//assigns the string s to the current string
String &assign (int n,char c);//assigns a value to the current string with n characters c
String &assign (const string &s,int start,int N);//assigned the current string from the n characters in the string s from start
String &assign (Const_iterator first,const_itertor last);//Assigning the part between first and last iterators to a string

Connection to String:
String &operator+= (const string &s);//Connect the string s to the end of the current string
String &append (const char *s); Concatenate the C-type string s to the end of the current string
String &append (const char *s,int N),//The first n characters of type C string s connect prompt to the end of the current string
String &append (const string &s); With operator+= ()
String &append (const string &s,int pos,int N);//n characters starting from Pos in string s connect prompt to the end of the current string
String &append (int n,char c); Adds n characters to the end of the current string C
String &append (Const_iterator first,const_iterator last);//Connect the part between the iterator first and last to the end of the current string

Comparison of String:
BOOL operator== (const string &s1,const string &s2) const;//compares two strings for equality
The operators ">", "<", ">=", "<=", "! =" are overloaded for string comparisons;
int compare (const string &s) const;//Compare the size of the current string and s
int compare (int pos, int n,const string &s) const;//compares the current string with the size of S of N characters starting from Pos
int compare (int pos, int n,const string &s,int pos2,int n2) const;// Compares the size of a string of n characters starting at the beginning of the current string from Pos with N2 characters starting with Pos2 in S
int compare (const char *s) const;
int compare (int pos, int n,const char *s) const;
int compare (int pos, int n,const char *s, int pos2) const;
The Compare function returns -1,== when > returns 1,< when return is 0
Substring of string:
String substr (int pos = 0,int n = NPOs) const;//Returns a string of n characters starting at Pos

Exchange of String:
void Swap (string &s2); Swap the current string with the value of S2

Lookup function for String class:
int find (char c, int pos = 0) const;//The position of the character C at the current string starting from the POS
int find (const char *s, int pos = 0) const;//Find the position of the string s in the current string starting from the POS
int find (const char *s, int pos, int n) const;//from Pos to find the position of the first n characters in the string s in the current string
int find (const string &s, int pos = 0) const;//Find the position of the string s in the current string starting from the POS
Returns the location when the lookup succeeds, and fails to return the value of String::npos
int RFind (char c, int pos = NPOs) const;//The position of the character C in the current string from the beginning of the POS
int rfind (const char *s, int pos = NPOs) const;
int rfind (const char *s, int pos, int n = npos) const;
int RFind (const string &s,int pos = NPOs) const;
Finds the position of the first n characters in the string s in the current string from the beginning of the POS, and returns the value of String::npos on failure.
int find_first_of (char c, int pos = 0) const;//Find the first occurrence of character C from Pos
int find_first_of (const char *s, int pos = 0) const;
int find_first_of (const char *s, int pos, int n) const;
int find_first_of (const string &s,int pos = 0) const;
Finds the position of the character in the first n-character array of s in the current string starting from Pos. Find failed return String::npos
int find_first_not_of (char c, int pos = 0) const;
int find_first_not_of (const char *s, int pos = 0) const;
int find_first_not_of (const char *s, int pos,int n) const;
int find_first_not_of (const string &s,int pos = 0) const;
Finds the first occurrence of a character not in the string s from the current string, fails back to String::npos
int find_last_of (char c, int pos = NPOs) const;
int find_last_of (const char *s, int pos = NPOs) const;
int find_last_of (const char *s, int pos, int n = npos) const;
int find_last_of (const string &s,int pos = NPOs) const;
int find_last_not_of (char c, int pos = NPOs) const;
int find_last_not_of (const char *s, int pos = NPOs) const;
int find_last_not_of (const char *s, int pos, int n) const;
int find_last_not_of (const string &s,int pos = NPOs) const;
Find_last_of and find_last_not_of are similar to find_first_of and find_first_not_of, except that they look forward from behind.

substitution function for String class:
String &replace (int p0, int n0,const char *s);//delete p0 characters from N0, then insert string s at P0
String &replace (int p0, int n0,const char *s, int n),//delete p0 start n0 characters, then insert first n characters of string s at P0
String &replace (int p0, int n0,const string &s),//delete p0 characters from N0, then insert string s at P0
String &replace (int p0, int n0,const string &s, int pos, int n),//delete p0 start N0 character, and then insert string s at P0 to start n characters from Pos
String &replace (int p0, int n0,int n, char c),//delete n0 characters beginning with p0, and then insert n characters C at p0
String &replace (iterator first0, iterator last0,const char *s);//replace the section between [First0,last0] with the string s
String &replace (iterator first0, iterator last0,const char *s, int n);//replace the section between [First0,last0] with the first n characters of S
String &replace (iterator first0, iterator last0,const string &s);//replace the section between [First0,last0] with string s
String &replace (iterator first0, iterator last0,int N, char c);//replace the section between [First0,last0] with n characters c
String &replace (iterator first0, iterator Last0,const_iterator first, const_iterator last);//Put [First0, LAST0) between the parts replaced by [First,last] between the strings

Insert function for String class: String &insert (int p0, const char *s);
String &insert (int p0, const char *s, int n);
String &insert (int p0,const string &s);
String &insert (int p0,const string &s, int pos, int n);
First 4 functions Insert the first n characters of the POS in the string s in the P0 position
String &insert (int p0, int n, char c);//This function inserts n characters c at p0
Iterator insert (iterator it, char c);//insert character C at it to return the position of the post-insertion iterator
void Insert (iterator it, Const_iterator first, const_iterator last);//insert characters between [first,last] in it
void Insert (iterator it, int n, char c);//insert n characters c in it

The delete function of the string class iterator erase (iterator first, iterator last);//delete all characters between [First,last] and return the position of the post-delete iterator
Iterator Erase (iterator it);//Remove the character that it points to, and return the location of the post-delete iterator
String &erase (int pos = 0, int n = npos);//delete the n characters starting at POS and return the modified string

The iterator processing of the string class:
The String class provides a forward and backward traversal of the iterator iterator, which provides syntax for accessing individual characters, similar to pointer operations, and iterators do not check scopes. The
declares an iterator variable with string::iterator or String::const_iterator, and Const_iterator does not allow the content of the iteration to be changed. Common iterator functions are:
Const_iterator begin () const;
iterator begin ();                //Returns the starting position of the string
Const_iterator end () const;
iterator end ();                    // Returns the position after the last character of String
Const_iterator rbegin () const;
iterator Rbegin ();                //Returns the position of the last character of String
Const_iterator rend () const;
Iterator rend ();                    //Returns the first character position of string before
Rbegin and rend are used to access from backward forward iterations by setting the iterator string::reverse_iterator,string: : Const_reverse_iterator implements

String Stream Processing:
Implemented by defining Ostringstream and Istringstream variables in the,<sstream> header file
For example:
String input ("Hello,this is a Test");
Istringstream is (input);
String S1,s2,s3,s4;
Is>>s1>>s2>>s3>>s4;//s1= "Hello,this", s2= "is", s3= "a", s4= "test"
Ostringstream OS;
os<<s1<<s2<<s3<<s4;
Cout<<os.str ();

the use of the standard C + + library String class std::string #include <string> std::string S1; std::string S3 (S2); std::string S2 ("This is a string"); begin gets the iterator that points to the beginning of the string end gets the iterator that points to the end of the string Rbegin Gets the iterator that points to the beginning of the reverse string Rend gets the iterator that points to the end of the reverse string size to get string sizes Length () is the same function as the size function max_size The maximum possible size of a string capacity The possible size of a string without reallocating memory empty to determine if null operator[] takes the first few elements, the equivalent of an array C_str get C-style const char* string data gets the string content address operator= assignment operator Reserve Space Swap swap function Insert Insertion Character Append Append characters push_back Append characters Erase Deleting a string clear clears all contents of the character container Resize Reallocate Space assign is the same as the assignment operator Replace Replace copy string to space Find lookup, returns the 0-based index number RFind Reverse Lookup Find_first_of finds any character in the containing substring and returns to the first position find_first_not_of Find does not contain any characters in a substring, return to the first position Find_last_of finds any character in the containing substring, returning to the last position find_last_not_of Find does not contain any characters in the substring, return to the last position substr (n1,len) gets a substring of length Len starting with a string from N1 Compare strings (all relational operators are supported) Compare comparing Strings operator+ String Links operator+= + = operator operator== judge whether equal operator!= judgment is not equal to operator< Judging whether it is less than operator>> reading a string from the input stream operator<< String writes to the output stream Getline reads a line from the input stream