C++学习（九）入门篇——String类

程序清单4.7  strtype1.cpp
//strtypel.cpp - - using the C++ string class
#include<iostream>
#include<string>
int main()
{
    using namespace std;
    char charr1[20];
    char charr2[20] = "jaguar";
    string str1;
    string str2 = "panther";

    cout << "Enter a kind of feline: ";
    cin >> charr1;
    cout << "Enter another kind of feline: ";
    cin >> str1;
    cin.get();
    cout << "Here are some felines:\n";
    cout << charr1 << " " << charr2 << " "
        << str1 << " " << str2 << endl;
    cout << "The third letter in " << charr2 << " is "
        << charr2[2] << endl;
    cout << "The third letter in " << str2 << " is "
        << str2[2] << endl;
    cin.get();

}

char charr1[20];
char charr2[20] = "jaguar";
string str1;
string str2 = "panther";
charr1=charr2;                      //不允许这么做
str1=str2;                             //可以

string str3;
str3 = str1+str2;
str1+=str2;

程序清单4.8 strtype2.cpp
//strtype2.cpp - - assigning,adding,and appending
#include<iostream>
#include<string>
int main()
{
    using namespace std;
    string s1 = "penguin";
    string s2, s3;

    cout << "You can assign one string object to another: s2=s1\n";
    s2 = s1;
    cout << "s1:" << s1 << ",s2:" << s2 << endl;
    cout << "You can assign a C-style string to a string object.\n";
    cout << "s2 = \"buzzard\"\n";
    s2 = "buzzard";
    cout << "s2: " << s2 << endl;
    cout << "You can concatenate strings:s3 = s2 + s1\n";
    s3 = s2 + s1;
    cout << "s3:" << s3 << endl;
    cout << "You can append strings.\n";
    s1 += s2;
    cout << "s1 += s2 yields s1 = " << s1 << endl;
    s2 += " for a day";
    cout << "s2 += \"for a day\" yields s2 = " << s2 << endl;
    cin.get();
}

strcpy(charr1,charr2);    //copy charr2 to charr1
strcat(charr1,charr2);    //append contents of charr2 to charr1

程序清单4.9  strtype3.cpp
//strtype3.cpp - - more string class features
#include<iostream>
#include<string>
#include<cstring>
int main()
{
    using namespace std;
    char charr1[20];
    char charr2[20] = "jaguar";
    string str1;
    string str2 = "panther";

    str1 = str2;
    strcpy_s(charr1,charr2);

    str1 += " paste";
    strcat_s(charr1, " juice");

    int len1 = str1.size();
    int len2 = strlen(charr1);

    cout << "The string " << str1 << " contains "
        << len1 << " characters.\n";
    cout << "The string " << charr1 << " contains "
        << len2 << " characters.\n";
    cin.get();
}

//strtype4.cpp - - line input
#include<iostream>
#include<string>
#include<cstring>
int main()
{
    using namespace std;
    char charr[20];
    string str;

    cout << "Length of string in charr before input:"
        << strlen(charr) << endl;
    cout << "Length of string in str before input:"
        << str.size() << endl;
    cout << "Enter a line of text:\n";
    cin.getline(charr, 20);
    cout << "You entered: " << charr << endl;
    cout << "Enter another line of text:\n";
    getline(cin, str);
    cout << "You entered:" << str << endl;
    cout << "Length of string in charr after input:"
        << strlen(charr) << endl;
    cout << "Length of string in str after input:"
        << str.size() << endl;
    cin.get();
}

wchar_t title[ ] =L"Chief Astrogator";
char16_t name[ ] =u"Felonia Ripova";
char32_t car[ ] =U"Humber Super Snipe";

cout<<R"(Jim "King" Tutt uses  "\n" instead of endl.)"<<'\n';

cout<<R"+*("(Who wouldn't?)",she whispered.)+*"<<endl;