string--c++ STL Learning

C++STL provides a string base character series container to handle strings, which can be interpreted as string classes, providing rich methods for adding delete \ replace \ Find and compare.
Using the string container, you need to include the header file declaration # include

Name of function	Description
Begin	Get the iterator that point to the beginning of the string
End	Get the iterator that points to the end of the string
Rbegin	Get the iterator that point to the beginning of the reverse string
Rend	Gets the iterator that points to the end of the reverse string
Size	Get the size of the string
Length	Same function as size function
Max_size	The maximum possible size of a string
Capacity	The possible size of a string without reallocating memory
Empty	Determines whether the empty
C_str	Get the C-style const char* string
Data	Get string content Address
Operator=	Assignment operator
Swap	Swap functions
Insert	Insert character
Append	Append character
Push_back	Append character
operator+=	+ = operator
Erase	Delete a string
Clear	Empty all contents of the character container
Resize	Reassign Space
Assign	Same as the assignment operator
Replace	Alternative
Copy	String to Space
Find	Find
RFind	Reverse Lookup
Find_first_of	Finds any character in the containing substring and returns to the first position
Find_first_not_of	Find any characters that do not contain substrings, return to the first position
Find_last_of	Finds any character in the containing substring and returns to the last position
Find_last_not_of	Find any characters that do not contain substrings, and return to the last position
Substr	Get substring
Compare	Comparing strings
operator+	String links
operator==	Judging if they are equal
operator!=	Judging if not equal to
operator<	Judging if it is less than
Operator>>	Reads a string from the input stream
operator<<	String writes to the output stream
Getline	Reads a line from the input stream

1. Creating a String Object

string s;  //生成一个空字符串sstring s(str) //拷贝构造函数 生成str的复制品string s(str,stridx) //将字符串str内"始于位置stridx"的部分当作字符串的初值string s(str,stridx,strlen) //将字符串str内"始于stridx且长度顶多strlen"的部分作为字符串的初值string s(cstr) //将C字符串作为s的初值string s(chars,chars_len) //将C字符串前chars_len个字符作为字符串s的初值。string s(num,c) //生成一个字符串，包含num个c字符string s(beg,end) //以区间beg;end(不包含end)内的字符作为字符串s的初值

A Length_error exception is thrown when the constructed string is too long to be expressed;

2. Accessing the elements of a string object

The elements of a string object are generally accessed randomly using subscript, and the subscript is counted from 0, and the string object element is a character (char), which must be clear;

const char &operator[](int n)const;const char &at(int n)const;char &operator[](int n);char &at(int n);//operator[]和at()均返回当前字符串中第n个字符的位置，但at函数提供范围检查，当越界时会抛出out_of_range异常，下标运算符[]不提供检查访问。const char *data()const;//返回一个非null终止的c字符数组const char *c_str()const;//返回一个以null终止的c字符串int copy(char *s, int n, int pos = 0) const;//把当前串中以pos开始的n个字符拷贝到以s为起始位置的字符数组中，返回实际拷贝的数目string s = "abc123456";cout << s[0] << endl;       //输出对象的首元素cout << s[0] - ‘a‘ << endl;  //两个相等的字符相减为0;

Method A of the 3.string Class A) =,assign ()//assigns a new value

s = "hello";s.assign("hello");              // basic_string& assign(const value_type* __s);s.assign(str); s.assign(str,1,3);              //如果str是"iamangel" 就是把"ama"赋给字符串s.assign(str,2,string::npos);   //把字符串str从索引值2开始到结尾赋给ss.assign("nico",5);             //把‘n‘ ‘I‘ ‘c‘ ‘o‘ ‘\0‘赋给字符串s.assign(5,‘x‘);                //把五个x赋给字符串string &operator=(const string &s);//把字符串s赋给当前字符串string &assign(const char *s);//用c类型字符串s赋值string &assign(const char *s,int n);//用c字符串s开始的n个字符赋值string &assign(const string &s);//把字符串s赋给当前字符串string &assign(int n,char c);//用n个字符c赋值给当前字符串string &assign(const string &s,int start,int n);//把字符串s中从start开始的n个字符赋给当前字符串string &assign(const_iterator first,const_itertor last);//把first和last迭代器之间的部分赋给字符串

b) Swap ()//Exchange two strings of content

void swap(string &s2);    //交换当前字符串与s2的值

c) +=,append (), push_back ()//Add characters at the tail

s += str; //加个字符串s += "my name is jiayp";  //加个C字符串s += ‘a‘; //加个字符s.append(str);s.append(str,1,3);  //截取str的第1~3位的字符串附在s的后面s.append(str,2,string::npos)    //截取str的第二到末尾的字符串附在s的后面string &operator+=(const string &s);//把字符串s连接到当前字符串的结尾 string &append(const char *s);            //把c类型字符串s连接到当前字符串结尾string &append(const char *s,int n);//把c类型字符串s的前n个字符连接到当前字符串结尾string &append(const string &s);    //同operator+=()string &append(const string &s,int pos,int n);//把字符串s中从pos开始的n个字符连接到当前字符串的结尾string &append(int n,char c);        //在当前字符串结尾添加n个字符cstring &append(const_iterator first,const_iterator last);//把迭代器first和last之间的部分连接到当前字符串的结尾s.push_back(‘!‘)      //这个函数只能增加单个字符

d) Insert ()//Insert character

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);//前4个函数在p0位置插入字符串s中pos开始的前n个字符string &insert(int p0, int n, char c);//此函数在p0处插入n个字符citerator insert(iterator it, char c);//在it处插入字符c，返回插入后迭代器的位置void insert(iterator it, const_iterator first, const_iterator last);//在it处插入[first，last）之间的字符void insert(iterator it, int n, char c);//在it处插入n个字符c

e) Erase ()//delete character

iterator erase(iterator first, iterator last);    //删除[first，last）之间的所有字符，返回删除后迭代器的位置iterator erase(iterator it);//删除it指向的字符，返回删除后迭代器的位置string &erase(int pos = 0, int n = npos);//删除pos开始的n个字符，返回修改后的字符串string s = "abc123456";string::iterator it = s.begin();  //定义迭代器变量，指向字符串对象首元素；s.erase(it+3);   //删除第三个元素，元素从位置0开始计数；s.erase(it, it+4);  //删除区间[0, 4)内所有元素的值；s.erase(s.begin(), s.begin()+4);  //删除区间[0, 4)内所有元素的值；s = "";   //清空字符串，或者直接用s.clear()；

f) Clear ()//delete all characters g) replace ()//Replace character

String &replace (int p0, int n0,const char *s);    Delete N0 characters starting from P0, and then insert a string sstring &replace (int p0, int n0,const char *s, int n) at P0;    Delete the N0 characters that start with P0, and then insert the first n characters of the string s at P0 string &replace (int p0, int n0,const string &s);    Delete N0 characters starting from P0, and then insert a string sstring &replace (int p0, int n0,const string &s, int pos, int n) at P0;    Delete the n0 characters that begin with P0, and then insert string s in the P0 string, starting with the N characters from the Pos. &replace (int p0, int n0,int n, char c);    Remove N0 characters starting with P0, then insert n characters at P0 CString &replace (iterator first0, iterator last0, const char *s);    Replace the section between [First0,last0] with the string sstring &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 the string sstring &replace (iterator first0, iterator last0, int n, char c); Replace the section between [First0,last0] with n characters CString &replace (iterator first0, iterator last0, const_iterator first, Const_    Iterator last); Replace the part between [First0,last0] with [First,last) between the strings 

h) +//concatenation string i) ==,!=,<,<=,>,>=,compare ()//Compare String

bool operator==(const string &s1,const string &s2)const;//比较两个字符串是否相等//运算符">","<",">=","<=","!="均被重载用于字符串的比较；int compare(const string &s) const;//比较当前字符串和s的大小int compare(int pos, int n, const string &s)const;//比较当前字符串从pos开始的n个字符组成的字符串与s的大小int compare(int pos, int n, const string &s, int pos2, int n2)const;//比较当前字符串从pos开始的n个字符组成的字符串与s中pos2开始的n2个字符组成的字符串的大小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

j) Size (), Length ()///return number of characters K) max_size ()///The maximum number of characters to return L) empty ()//Determine if the string is empty

cout << s.empty() << endl;s.clear(); //或者是 s = "";cout << s.empty() << endl;

m) Capacity ()//return the character capacity before redistribution N) reserve ()//retain a certain amount of memory to accommodate a certain number of characters

string s = "0123456789";reverse(s.begin(), s.end());cout << s << endl;

o) [], at ()//Access single character P) >>,getline ()//read a value from stream Q) <<//write a value to STREAMR) copy ()//Assign a value to a c_strings) c_str ()// Returns the content as C_string T) data ()//returns the content as a character array U) substr ()//Returns a substring

string substr(int pos = 0,int n = npos) const;//返回pos开始的n个字符组成的字符串

V) Find function

int find (char c, int pos = 0) const;//from the Pos to find the character C at the position of the current string int find (const char *s, int pos = 0) const;//from the Pos to find the string s bit in the current string Set 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) Cons t;//from Pos to find the position of the string s in the current string//Find successful when the location returned, failed to return the value of String::npos int rfind (char c, int pos = NPOs) const;// From the POS, look forward to the character C in the current string position int rfind (const char *s, int pos = NPOs) const;int rfind (const char *s, int pos, int n = NPOs) cons T;int rfind (const string &s,int pos = NPOs) const;//The position of the first n characters in the string s in the current string from the beginning of the POS, from the back forward, and returns a string when unsuccessful: The value of NPOs int find_first_of (char c, int pos = 0) const;//from the Pos to find the first occurrence of the character C position int find_first_of (const char *s, int pos = 0) con St;int find_first_of (const char *s, int pos, int n) const;int find_first_of (const string &s, int pos = 0) const;//from POS Begins the search for the position of the character in the first n-character array of s in the current string. Lookup failed to 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) Cons T;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;//Find the first character not in string s from the current string Present position, failed return 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_las t_not_of (const char *s, int pos, int n) const;int find_last_not_of (const string &s, int pos = NPOs) const;//find_last_ The and find_last_not_of are similar to find_first_of and find_first_not_of, except that they look forward to cout << s.find (' C ') << Endl;  Finds the first character ' C ', returns its subscript value; cout << s.find ("C") << Endl; Finds the first substring "C", returns its subscript value; cout << s.find ("Cat") << Endl;  Finds the first substring "cat", returns its subscript value; cout << s.find ("DOGC") << Endl; Not found, returned;

W) begin () end ()//provide an STL-like iterator support

const_iterator begin()const;iterator begin();                //返回string的起始位置const_iterator end()const;iterator end();                    //返回string的最后一个字符后面的位置

x) Rbegin () rend ()//Reverse iterator

const_iterator rbegin()const;iterator rbegin();                //返回string的最后一个字符的位置const_iterator rend()const;iterator rend();                    //返回string第一个字符位置的前面//rbegin和rend用于从后向前的迭代访问，通过设置迭代器string::reverse_iterator,string::const_reverse_iterator实现

Y) Get_allocator ()//Return Configurator

string--c++ STL Learning