C++ std::string 完整參考手冊

std::string 是 C++ 標準庫提供的強大字串類別，封裝了記憶體管理與豐富操作介面，可視為字元容器使用。本文整理所有成員函數供查閱。

1. 建構函數

string();                              // 空字串
string(size_type n, char c);           // n 個 c
string(const char* s);                 // C 風格字串
string(const char* s, size_type n);    // C 字串前 n 字元
string(const string& str, size_type pos, size_type n = npos); // 子串
template 
string(InputIt first, InputIt last);   // 迭代器範圍

2. 運算子

== != < > <= >= + += []

3. 追加

string& append(const string& str);
string& append(const char* s);
string& append(const string& str, size_type pos, size_type n);
string& append(const char* s, size_type n);
string& append(size_type n, char c);
string& append(InputIt first, InputIt last);
void push_back(char c);

4. 指派

string& assign(const string& str);
string& assign(const char* s);
string& assign(const char* s, size_type n);
string& assign(const string& str, size_type pos, size_type n);
string& assign(size_type n, char c);
string& assign(InputIt first, InputIt last);

5. 比較

int compare(const string& str) const;
int compare(size_type pos, size_type n, const string& str) const;
int compare(size_type pos1, size_type n1, const string& str, size_type pos2, size_type n2) const;
int compare(const char* s) const;
int compare(size_type pos, size_type n, const char* s) const;
int compare(size_type pos, size_type n, const char* s, size_type n2) const;
// 回傳 <0, 0, >0 分別對應 <, ==, >

6. 刪除

iterator erase(iterator first, iterator last);
iterator erase(iterator pos);
string& erase(size_type pos = 0, size_type n = npos);

7. 插入

iterator insert(iterator pos, char c);
string& insert(size_type pos, const string& str);
string& insert(size_type pos, const char* s);
string& insert(size_type pos, const string& str, size_type pos2, size_type n);
string& insert(size_type pos, const char* s, size_type n);
string& insert(size_type pos, size_type n, char c);
void insert(iterator pos, size_type n, char c);
void insert(iterator pos, InputIt first, InputIt last);

8. 替換

string& replace(size_type pos, size_type n, const string& str);
string& replace(size_type pos1, size_type n1, const string& str, size_type pos2, size_type n2);
string& replace(size_type pos, size_type n, const char* s);
string& replace(size_type pos, size_type n1, const char* s, size_type n2);
string& replace(size_type pos, size_type n1, size_type n2, char c);
string& replace(iterator first, iterator last, const string& str);
string& replace(iterator first, iterator last, const char* s);
string& replace(iterator first, iterator last, const char* s, size_type n);
string& replace(iterator first, iterator last, size_type n, char c);

9. 查找

size_type find(const string& str, size_type pos = 0) const;
size_type find(const char* s, size_type pos = 0) const;
size_type find(const char* s, size_type pos, size_type n) const;
size_type find(char c, size_type pos = 0) const;

size_type rfind(const string& str, size_type pos = npos) const;
size_type rfind(const char* s, size_type pos = npos) const;
size_type rfind(const char* s, size_type pos, size_type n) const;
size_type rfind(char c, size_type pos = npos) const;

size_type find_first_of(const string& str, size_type pos = 0) const;
size_type find_last_of(const string& str, size_type pos = npos) const;
size_type find_first_not_of(const string& str, size_type pos = 0) const;
size_type find_last_not_of(const string& str, size_type pos = npos) const;
// 找不到回傳 string::npos (通常為 -1)

10. 其他常用函數

11. 實戰範例

#include 
#include 
#include 
using namespace std;

int main() {
    string s1;
    cin >> s1;                    // 遇空白停止
    getline(cin, s1);             // 整行讀取

    string s2 = "hello";
    string s3(5, 'x');            // "xxxxx"
    string s4(s2, 1, 3);          // "ell"

    char c = s2[1];               // 'e'
    c = s2.at(2);                 // 'l' (含檢查)

    cout << "長度: " << s2.length() << endl;
    cout << "容量: " << s2.capacity() << endl;

    s2 += " world";               // 連接
    s2.append("!");

    if (s2 == "hello world!")     // 比較
        cout << "相等" << endl;

    string sub = s2.substr(6, 5); // "world"
    s2.replace(6, 5, "C++");      // "hello C++!"

    s2.insert(5, ",");            // "hello, C++!"
    s2.erase(5, 1);               // 刪除 ','

    // 字串流分割
    string line("hello this is a test");
    istringstream iss(line);
    string word;
    while (iss >> word)
        cout << word << '|';
    return 0;
}