string类中的各种函数
1,构造一个字符串
string s“welcome to c++”;
2,追加字符串
string s1(“welcome”);
s1.append(“ to c++”);
cout<<s1<<endl;
相应的还有s1.append(“ to c++”,0,5)&s1.append(“ to c++”,5)&s1.append(4,‘g’)
知道这几种输出的不同。
3,字符串的赋值
string s1(“welcome”);
s1.assign(“ to c++”);
相应的还有s1.assign(“ to c++”,0,5)&s1.assign(“ to c++”,5)&s1.assign(4,‘g’)
同append掌握assign。
4,函数at,clear,erase,empty
string s1(“welcome”);
cout<<s.1(3)<<endl;//输出第三个字符
cout<<s1.erase(2,3);//跳过前两个字符删除3到5个字符
s1.clear();//现在是空字符串
cout<<s1.empty()<<endl;//检查是否为空字符串
5,函数length,size,capacity,c_str()
分别为获取字符串长度,大小.分配的内存空间大小,c_str()返回一个c字符串。
string s1(“welcome”);
cout<<s1.length()<<endl;同理可获得size,capacity
6,字符串的比较
string s1(“welcome”);
string s2(“welcomg”);
cout<<s1.compare(s2)<<endl;//return -1
cout<<s2.compare(s1)<<endl;//return 1
cout<<s1.compare("welcome");//return 0
7,获取字符串
string s1(“welcome”);
cout<<s1.substr(0,1)<<endl;//return w
cout<<s1.substr(3)<<endl;//return come
cout<<s1.substr(3,3)<<endl;//return com
8,字符串的替换和插入
string s1.(“welcome to html”)
s1.insert(11,"c++ and ");
cout<<s1<<endl;//s1 become welcome to c++ and html
string s2("AA");
s2.insert(1,4,'B');
cout<<s2<<endl;//s2 become to ABBBBA
string s3("welcome to html")
s3.replace(11,4,"c++");
cout<<s3<<endl;//s3 become welcome to c++