STL中string的基本用法范例

#include <iostream>

#include <string>

using namespace std;

//string转char*

void s_c()

{

    string str="hello word";

    const char* cstr = str.c_str();

    cout<<cstr<<endl;

}

//char* 转string

void c_s()

{

    char* c = "hello word";

    string s(c);

    cout<<s<<endl;

}

//string 赋值操作

void string_some()

{

    //创建一个空的字符串

    string str="hello word";

    //使用str 初始化str2

    string str2(str);

    //使用char*初始化string；

    const char* c= "hello word";

    string str3(c);

    cout<<"str3="<<str3<<endl;

    //字符赋值给当前字符串

    char s_si[]="2";

    string str4(s_si);

    cout<<"str4="<<str4<<endl;

    //使用n个字符初始化c

    int n_i = 5;

    char n_c[] = "s";

    string str5(n_i,*n_c);

    cout<<"str5="<<str5<<endl;

    //将s从start开始n个字符赋值给字符串

    string s ="ABCDEFG";

    int start = 2;

    int n =6;

    string str6(s,start,n);

    cout<<"str6="<<str6<<endl;

    //string 通过[],at方式取字符 at方式取字符如果越界可以被异常捕获

    string str7="1234567";

    str[1];

    str.at(1);

}

//string 拼接操作

void string_pin()

{

    //+=拼接字符串

    string str = "12345";

    string str2 = "67890";

    str += str2;

    cout<<"str="<<str<<endl;

    //+=拼接char*

    char * c="1234";

    string str3="5678";

    str3+=c;

    cout<<"str3="<<str3<<endl;

    //+=拼接char字符

    char c_s[]="cd";

    string str4 = "ab";

    str4+=c_s;

    cout<<"str4="<<str4<<endl;

    //连接string到当前字符串尾部

    string str5="123";

    str4.append(str5);

    cout<<"str4="<<str4<<endl;

    //连接char*到当前字符串尾部

    const char* c_s1="cdefg";

    str5.append(c_s1);

    cout<<"str5="<<str5<<endl;

    //连接char 到当前字符串尾部

    const char c_s2[]="0987";

    string str6="5432";

    str6.append(c_s2);

    cout<<"str6"<<str6<<endl;

    //吧str7中p开始的n个字符串链接到当前字符串尾部

    string str7 = "abcdef";

    int p=0;int n =2;

    str4.append(str7,p,n);

    cout<<"str4="<<str4<<endl;

    //在当前字符串结尾添加n个字符串a

    char c_8[] = "1234";

    int n_8 = 2;

    string str8 = "asd";

    str8.append(n_8,*c_8);

    cout<<"str8="<<str8<<endl;

}

//string 查找和替换

void string_find()

{

     //find 从n开始查找s所在的位置

     string str = "1234567890acsdefgh";

     string s = "6";

     int n = 4;

     int f_s = str.find(s,n);

     cout<<"f_s="<<f_s<<endl;

     //char*类型同上

     const char* s_2 = "7";

     int n_2 =2;

     int f_s1=str.find(s_2,n_2);

     cout<<"f_s1="<<f_s1<<endl;

     //

     string s_3="e";

     int n_3=13;

     int n_3_2 = 8;

     int f_s2 = str.find(s_2,8,n_3_2);

     cout<<"f_s2="<<f_s2<<endl;

     //rfind 从后向前查

     string s_r = "3";

     int f_r = str.rfind(s_r,n);

     cout<<"f_r="<<f_r<<endl;

}

//string比较操作

//compare 大于时返回1 小于时返回-1，等于时返回0，比较时参考字典顺序

void str_compare()

{

    //string 比较

    string s="1";

    string c="1";

    int comp = s.compare(c);

    cout<<"comp="<<comp<<endl;

    //char* 比较

    const char* c_c="2";

    int c_s_comp = s.compare(c_c);

    cout<<"c_s_comp="<<c_s_comp<<endl;

    //copy子串

    string str ="1234567890";

    int sr_c = 5;

    int po_c = 3;

    string so_str = str.substr(sr_c,po_c);

    cout<<"so_str="<<so_str<<endl;

}

//string 插入和删除

void de_str()

{

    //取str中第五个以后的字符插入到str_num中

    string str = "abcdefgh";

    string str_num = "123456789";

    int num = 5;

    string s = str.insert(num,str_num);

    cout<<"str="<<s<<endl;

    //删除从第pos位置开始的pos_n个元素

    int pos = 3;

    int pos_n = 2;

    s.erase(pos,pos_n);

    cout<<"str="<<s<<endl;

}

int main()

{

    s_c();

    c_s();

    string_some();

    string_pin();

    string_find();

    str_compare();

    de_str();

    cout << ".............." << endl;

    return 0;

}