可以用string類而不是字符數組來存儲字符串，string更加簡單

要是用string類，則要在程序中包含頭文件string，且位於std名稱空間中，string類隱藏了字符串的數組性質，可以像處理普通變量那樣處理字符串

程序清單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();

}

輸出結果：

string對象聲明為簡單變量

char數組為一組用於存儲字符串的char存儲單元，string類為一個存儲字符串的實體

除了數組初始化可用列表初始化，也適用於字符串初始化

char first_date[ ] ={"Le Chapon Dodu"};

string second_date={"Le Chapon Dodu"};

char third_date[ ] {"Le Chapon Dodu"};

string forth_date {"Le Chapon Dodu"};

不能將一個數組賦給另一個數組，但可以將一個string對象賦給另一個string對象

char charr1[20];
char charr2[20] = "jaguar";
string str1;
string str2 = "panther";
charr1=charr2;                      //不允許這麽做
str1=str2;                             //可以

string類簡化了字符串合並操作

還可以將兩個string對象合並起來

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

程序清單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();
}

結果：

在C++新增string類前，還是要完成給字符串賦值，用頭文件cstring中的函數來完成，用函數strcpy（）將字符串復制到字符數組中，用strcat（）將字符串附加到字符數組末尾

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

程序清單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();
}

輸出：

函數strlen（）是一個常規函數，返回該字符串包含的字符數。

str1是一個對象，而size（）是一個類對象，所以這樣調用str1.size（）

C++學習（九）入門篇——String類