笔记：string(C++标准库)

标准C++提供了两种字符串：

1.C语言风格的以'\0'字符结尾的字符数组

2.字符串类string。（Boost中又为string扩充了一些函数） 

总结一下std::string函数用法。

操作符：

string& operator=( const string& s );

string& operator=( const char* s );

string& operator=( char ch );

string operator+(const string& s1, const string& s2 );

string operator+(const char* s, const string& s2 );

string operator+( char c, const string& s2 );

string operator+( const string& s1, const char* s );

string operator+( const string& s1, char c );

bool operator==(const string& c1, const string& c2);

操作字符串：

附加：append(...)

赋值：assign(...)

复制：copy(...)

删除：erase(...)

清空：clear()

交换：void swap( const container& from );

替换：

string& replace( size_type index, size_type num, const string& str );

string& replace( size_type index1, size_type num1, const string& str, size_type index2, size_type num2 );

string& replace( size_type index, size_type num, const char* str );//用str替换从index开始的num个字符

string& replace( size_type index, size_type num1, const char* str, size_type num2 );

string& replace( size_type index, size_type num1, size_type num2, char ch );

string& replace( iterator start, iterator end, const string& str );

string& replace( iterator start, iterator end, const char* str );

string& replace( iterator start, iterator end, const char* str, size_type num );

string& replace( iterator start, iterator end, size_type num, char ch );

插入：

iterator insert( iterator i, const char& ch );

string& insert( size_type index, const string& str );

string& insert( size_type index, const char* str );//在index位置插入字符串str

string& insert( size_type index1, const string& str, size_type index2, size_type num );

string& insert( size_type index, const char* str, size_type num );

string& insert( size_type index, size_type num, char ch );

void insert( iterator i, size_type num, const char& ch );

void insert( iterator i, iterator start, iterator end );

 

查询字符串(搜索)：

size_type find( const string& str, size_type index );

size_type find( const char* str, size_type index );//从index开始查找字符串str在当前串中的位置

size_type find( const char* str, size_type index, size_type length );

size_type find( char ch, size_type index );

size_type rfind( const string& str, size_type index );

size_type rfind( const char* str, size_type index );//从index开始从后向前查找字符串str在当前串中的位置

size_type rfind( const char* str, size_type index, size_type num );

size_type rfind( char ch, size_type index );

find_first_not_of(...) //从当前串中查找第一个不在串str中的字符出现的位置

find_first_of(...) //查找第一个出现的字符串

find_last_not_of(...) //find last absence of characters

find_last_of(...) //find last occurrence of characters

求子串

string substr( size_type index, size_type num = npos );//返回index开始的num个字符组成的字符串

转换为C语言字符串  const char* c_str();

比较字符串  compare(...)//负整数 this < str; 0 this == str; 正整数 this > str

判断字符串是否为空  bool empty() const;

求长度  size_type length() const;

#include <iostream>
#include <string>
using namespace std;

int main(int argc, char *argv[])
{
    //g++编译器
    string str1("Hello World!");
    string str2 = "welcome to China.";
    string str3 = "books";
    string str4 = "books";
    char buf[] = "12345678ab";
    string s1 = "I like go shopping.";
    string s2 = "effective C++";
    string s3 = "My cat's breath smells like cat food.";
    string s4 = "Tom is cat.";

    str1.append( str2, 3, 10 );//str1:"Hello World!come to Ch"
    str1.assign( str2, 4, 3 );//str1:"ome"
    str1.clear();//str1:""
    str3.compare(str4);//返回0
    str3.copy(buf,3);//buf:boo45678ab
    str1.empty();//返回true

    s1.erase( 1, 5 );//s1:"I go shopping."
    s1.erase( 3 );//s1:"I g"
    s1.erase();//s1:""

    int len = s2.length();//13
    string::size_type index;
    index = s2.find("abc",0);//失败返回string::npos 即-1
    index = s2.find("C++",0);//10

    int loc;
    loc = s3.rfind( "breath", 8 );//-1
    loc = s3.rfind( "breath", 20 );//9

    //cout << s2 << endl;
    //cout << s3 << endl;
    s2.swap(s3);
    //cout << s2 << endl;
    //cout << s3 << endl;

    s4.replace(4,2,"is not");//s4:"Tom is not cat."

    s4.insert(1,"abc");//s4:"Tabcom is not cat."

    string sTemp = s4.substr(7,6);//sTemp:"is not"


    return 0;
}