Develop Notes: C++ string class

C++的string类里提供了很多的函数，包含字符串的查找，替换，等等操作。尽管它并没有比如javascript之类的字符操作函数多样，但是各种功能的字符查找都可以通过这些基本的函数实现。
javascript的字符串对象string object的相关内容见
http://www.w3schools.com/jsref/jsref_obj_string.asp
XPATH的字符串对象string object可以参考：
http://www.w3.org/TR/xpath#section-String-Functions
http://www.w3schools.com/xpath/xpath_functions.asp#string

http://www.w3schools.com 是个好网站

参考可以看
http://www.cppreference.com/cppstring/index.html
每一个条目的链接页都有示例。

C++ Strings

Display all entries for C++ Strings on one page, or view entries individually:

String constructors	create strings from arrays of characters and other strings
String operators	concatenate strings, assign strings, use strings for I/O, compare strings
append	append characters and strings onto a string
assign	give a string values from strings of characters and other C++ strings
at	returns an element at a specific location
begin	returns an iterator to the beginning of the string
c_str	returns a standard C character array version of the string
capacity	returns the number of elements that the string can hold
clear	removes all elements from the string
compare	compares two strings
copy	copies characters from a string into an array
data	returns a pointer to the first character of a string
empty	true if the string has no elements
end	returns an iterator just past the last element of a string
erase	removes elements from a string
find	find characters in the string
find_first_not_of	find first absence of characters
find_first_of	find first occurrence of characters
find_last_not_of	find last absence of characters
find_last_of	find last occurrence of characters
getline	read data from an I/O stream into a string
insert	insert characters into a string
length	returns the length of the string
max_size	returns the maximum number of elements that the string can hold
push_back	add an element to the end of the string
rbegin	returns a reverse_iterator to the end of the string
rend	returns a reverse_iterator to the beginning of the string
replace	replace characters in the string
reserve	sets the minimum capacity of the string
resize	change the size of the string
rfind	find the last occurrence of a substring
size	returns the number of items in the string
substr	returns a certain substring
swap	swap the contents of this string with another

这里还有一个列表，来自
http://www.bgsu.edu/departments/compsci/docs/string.html

C++ String Class

The C++ Standard Template Library (STL) contains a string class that is used in several computer science classes. In order to use the string class you should include the following statements:
#include using std::string;

The following examples assume these declarations and initial values for each:

string s = "abc def abc"; string s2 = "abcde uvwxyz"; char c; char ch[] = "aba daba do"; char *cp = ch; unsigned int i;

Stream input	`cin >> s;`	Changes the value of s to the value read in. The value stops at whitespace.
Stream output	`cout <<>`	Writes the string to the specified output stream.
Line input	`getline(cin, s);`	Reads everything up to the next newline character and puts the result into the specified string variable.
Assignment	`s = s2;s = "abc"; s = ch; s = cp;`	A string literal or a string variable or a character array can be assigned to a string variable. The last two assignments have the same effect.
Subscript	`s[1] = 'c'; c = s[1];`	Changes s to equal "acc def abc" Sets c to 'b'. The subscript operator returns a char value, not a string value.
Length	`i = s.length(); i = s.size();`	Either example sets i to the current length of the string s
Empty?	`if(s.empty()) i++; if(s == "") i++;`	Both examples add 1 to i if string s is now empty
Relational operators	`if (s <>`	Uses ASCII code to determine which string is smaller. Here the condition is true because a space comes before letter d
Concatenation	`s2 = s2 + "x"; s2 += "x";`	Both examples add x to the end of s2
Substring	`s = s2.substr(1,4); s = s2.substr(1,50);`	The first example starts in position 1 of s2 and takes 4 characters, setting s to "bcde". In the second example, s is set to "bcde uvwxyz". If the length specified is longer than the remaining number of characters, the rest of the string is used. The first position in a string is position 0.
Substring replace	`s.replace(4,3,"x");`	Replaces the three characters of s beginning in position 4 with the character x. Variable s is set to "abc x abc".
Substring removal	`s.erase(4,5); s.erase(4);`	Removes the five characters starting in position 4 of s. The new value of s is "abc bc". Remove from position 4 to end of string. The new value of s is "abc ".
Character array to string	`s = ch;`	Converts character array ch into string s.
String to character array	`cp = s.c_str();`	Pointer cp points to a character array with the same characters as s.
Pattern matching	`i = s.find("ab",4);` `if(s.rfind("ab",4) != string::npos) cout << "Yes" <<>`	The first example returns the position of the substring "ab" starting the search in position 4. Sets i to 8. The find and rfind functions return the unsigned int string::npos if substring not found. The second example searches from right to left starting at position 4. Since the substring is found, the word Yes is printed.

Because of a bug in the bgunix version of the g++ compiler, writing a string variable under setw control doesn't work. You need to use the c_str member function, like this:
cout <<>

C语言的字符处理库如下
http://www.cplusplus.com/reference/clibrary/cstring/

cstring (string.h)

header

C Strings

This header file defines several functions to manipulate C strings and arrays.