技術標籤：C++基礎c++字串stl

1 string

string內部含有一個char*字串

2 string構造方式

• 無參構造

string str;

• 字串構造

string str("abcd");

• 拷貝構造
• n個相同字元

string str(10, 'k');  //初始化為10個k

3 string賦值操作

可以有以下操作:

void string_test() {
    string str1;
    str1 = "str1";
    cout << "str1 = " << str1 << endl;
    string str2 = str1;
    cout << "str2 = " << str2 << endl;
    string str3 = "a";
    cout << "str3 = " << str3 << endl;
    string str4;
    str4.assign("str4");
    cout << "str4 = " << str4 << endl;
    string str5;
    str5.assign("123456789", 5);
    cout << "str5 = " << str5 << endl;
    string str6;
    str6.assign(str5);
    cout << "str6 = " << str6 << endl;
    string str7;
    str7.assign(10, 'k');
    cout << "str7 = " << str7 << endl;
}
 

結果為:

4 string拼接

可以使用的是 += 以及append, 例子如下:

void string_test1() {
    string str1 = "str1";
    str1 += "str";
    cout << "str1 = " << str1 << endl;
    str1 = "str1";
    str1 += 's';
    cout << "str1 = " << str1 << endl;
    str1 = "str1";
    string str2 = "str2";
    str1 += str2;
    cout << "str1 = " << str1 << endl;
    str1 = "str1";
    str1.append("str");
    cout << "str1 = " << str1 << endl;
    str1 = "str1";
    str1.append(str2);
    cout << "str1 = " << str1 << endl;
    str1 = "str1";
    str1.append("abcdefg", 4);            //拼前四個字元
    cout << "str1 = " << str1 << endl;
    str1 = "str1";
    str1.append("0123456789", 2, 3);      //從第二(從0開始數)個字元開始拼三個字元
    cout << "str1 = " << str1 << endl;
    str1 = "str1";
}
 

5 查詢和替換

find測試:

void string_find_test() {
    string str1 = "abcdefg";
    int position = str1.find("de", 2);            //find有兩個引數, 第一個是要查詢的字元
    cout << "position: " << position << endl;     //或者子串, 第二個引數是開始查詢的位置,
    position = str1.find("df", 2);                //第二個引數的預設值為0,返回值是找到的
    cout << "position: " << position << endl;     //起始位置的下標,如果未找到就返回-1
    position = str1.rfind("de", 2);               //rfind跟find的區別是:rfind是從右向左
    cout << "position: " << position << endl;     //查詢.
}