Note C++ string

C++stringのいくつかの操作記録
#include

定義

#include 
#include 

int begin = 0;
int mid = 2;
int len = 3;
int end = 8;
int pos = 0;

構造

string str = "A";
string str1(str);
string str2("A");
string str3("abcd", len);   // str3 == "abc"
string str4("abcd", begin, len); // str4 = "abcd" begin  ，len 
string str5(len, 'a'); //    len 'a'

通常length、size、capacity、empty、resize、reserve

// 2     
len = str.length(); //   
len = str.size();   //   
int capacity = str.capacity(); //   

str.resize(len);        // str    len  ,   \0  
str.resize(len, 'a');   // str    len  ,   'a'  
str.reserve(len);       //         

bool isEmpty = str.empty();

push_を追加back、append、insert

str.push_back('a');
str.append("ABC");

//     
str.insert(begin, len, 'a'); // str begin    len 'a'  
str.insert(begin, "abc"); // begin    
str.insert(begin, "abc", len); // begin    "abc" len   
str.insert(begin, "abc", begin, len); // begin     "abc" begin  ,len 

//      
// iterator insert(const const_iterator _Where, _CRT_GUARDOVERFLOW const size_type _Count, const _Elem _Ch)
str.insert(str.begin(), len, 'a');
// iterator insert(const const_iterator _Where, const _Iter _First, const _Iter _Last)
str.insert(str.begin(), str2.begin(), str2.end());

erase、clear、assign

を削除

str.erase(mid); //   mid  ，      
str.erase(mid, len);  //   mid  ，  len 
str.clear();

str.assign("abc");  //   str，   "abc"
str.assign("abcd", len); //   ，  len   
str.assign("abccc", begin, len);    //   ， begin  ，  len

swap、replace

を修正

str.swap(str1); //   str1 str
str.replace(begin, len, "abc"); //   begin  ，  len  

find、rfind、find_を検索first_of、find_last_of string::size_type、string::npos

//size_t find(const string & str, size_t pos = 0) const;
//size_t find(const char* s, size_t pos, size_t n) const;
//size_t find(const char* s, size_t pos = 0) const;
//size_t find(char c, size_t pos = 0) const;
// pos       n        n   
pos = str.find('a'); //       ，    -1
pos = str.find("abc");
pos = str.find('a', begin); //  begin     
pos = str.find("abc", begin, len); //  begin      "abc"  len  

//     ，      
pos = str.rfind('a');
pos = str.rfind("abc");
pos = str.rfind('a', begin); // begin  ，   
pos = str.rfind("abc", begin, len);

//size_t find_first_of(const string & str, size_t pos = 0) const;
//size_t find_first_of(const char* s, size_t pos, size_t n) const;
//size_t find_first_of(const char* s, size_t pos = 0) const;
//size_t find_first_of(char c, size_t pos = 0) const;
// pos       n        n   
//                 
str.find_first_of("abc");
str.find_first_of("abc", begin);
str.find_first_of("abc", begin, len);

//size_t find_last_of(const string & str, size_t pos = npos) const noexcept;
//size_t find_last_of(const char* s, size_t pos = npos) const;
//size_t find_last_of(const char* s, size_t pos, size_t n) const;
//size_t find_last_of(char c, size_t pos = npos) const noexcept;

// string::size_type
string::size_type pos = str.find(str2);
// string::npos
if (pos == string::npos) { }

    //       
    if (!s.empty()) {
        s.erase(0,s.find_first_not_of(" "));
        s.erase(s.find_last_not_of(" ") + 1);
    }

サブストリングsubstr

// string substr(size_t pos = 0, size_t len = npos) const;
// pos             。              0,    0。
// len        
str2 = str.substr(begin);
str2 = str.substr(begin, len);

反転reverse

// algorithm
reverse(str.begin(), str.end());    //   

変換大文字と小文字transform、::toupper、::tolower

string strTrans = "A";
transform(strTrans.begin(), strTrans.end(), strTrans.begin(), ::toupper);
transform(strTrans.begin(), strTrans.end(), strTrans.begin(), ::tolower);

比較compare

// compare
//     0,   ASCII        
//int compare(const basic_string & s) const;
//int compare(const Ch * p) const;
//int compare(size_type pos, size_type n, const basic_string & s) const;
//int compare(size_type pos, size_type n, const basic_string & s, size_type pos2, size_type n2) const;
//int compare(size_type pos, size_type n, const Ch * p, size_type = npos) const;
str.compare("abc");

to_string

//            
//std::string to_string(int value);
//std::string to_string(long value);
//std::string to_string(long long value);
//std::string to_string(unsigned value);
//std::string to_string(unsigned long value);
//std::string to_string(unsigned long long value);
//std::string to_string(float value);
//std::string to_string(double value);
//std::string to_string(long double value);
str = to_string(1);

その他:c_str、data、copy

// c_str()    const char*  ，           
// const char* string::c_str() const
const char* strChar = str.c_str();

// const char* string::data() const
// data(): c_str()  ，              
strChar = str.data();

// size_type copy(_Out_writes_(_Count) _Elem* const _Ptr, size_type _Count, const size_type _Off = 0) const
char charAry[20] = { 0 };
str.copy(charAry, len, begin); // begin  ，  len    

 

#include 
#include 
#include 

using namespace std;

class Solution {
public:
    void Test() {
        int begin = 0;
        int mid = 2;
        int len = 3;
        int end = 8;
        int pos = 0;

        // 1   
        string str = "A";
        string str1(str);
        string str2("A");
        string str3("abcd", len);   // str3 == "abc"
        string str4("abcd", begin, len); // str4 = "abcd" begin  ，len 
        string str5(len, 'a'); //    len 'a'

        // 2     
        len = str.length(); //   
        len = str.size();   //   
        int capacity = str.capacity(); //   

        str.resize(len);        // str    len  ,   \0  
        str.resize(len, 'a');   // str    len  ,   'a'  
        str.reserve(len);       //         

        bool isEmpty = str.empty();

        //  
        str.push_back('a');
        str.append("ABC");

        //     
        str.insert(begin, len, 'a'); // str begin    len 'a'  
        str.insert(begin, "abc"); // begin    
        str.insert(begin, "abc", len); // begin    "abc" len   
        str.insert(begin, "abc", begin, len); // begin     "abc" begin  ,len 

        //      
        // iterator insert(const const_iterator _Where, _CRT_GUARDOVERFLOW const size_type _Count, const _Elem _Ch)
        str.insert(str.begin(), len, 'a');
        // iterator insert(const const_iterator _Where, const _Iter _First, const _Iter _Last)
        str.insert(str.begin(), str2.begin(), str2.end());


        //  
        str.erase(mid); //   mid  ，      
        str.erase(mid, len);  //   mid  ，  len 
        str.clear();

        str.assign("abc");  //   str，   "abc"
        str.assign("abcd", len); //   ，  len   
        str.assign("abccc", begin, len);    //   ， begin  ，  len

        //  
        str.swap(str1); //   str1 str
        str.replace(begin, len, "abc"); //   begin  ，  len  

        //  
        //size_t find(const string & str, size_t pos = 0) const;
        //size_t find(const char* s, size_t pos, size_t n) const;
        //size_t find(const char* s, size_t pos = 0) const;
        //size_t find(char c, size_t pos = 0) const;
        // pos       n        n   
        pos = str.find('a'); //       ，    -1
        pos = str.find("abc");
        pos = str.find('a', begin); //  begin     
        pos = str.find("abc", begin, len); //  begin      "abc"  len  

        //     ，      
        pos = str.rfind('a');
        pos = str.rfind("abc");
        pos = str.rfind('a', begin); // begin  ，   
        pos = str.rfind("abc", begin, len);

        //size_t find_first_of(const string & str, size_t pos = 0) const;
        //size_t find_first_of(const char* s, size_t pos, size_t n) const;
        //size_t find_first_of(const char* s, size_t pos = 0) const;
        //size_t find_first_of(char c, size_t pos = 0) const;
        // pos       n        n   
        //                 
        str.find_first_of("abc");
        str.find_first_of("abc", begin);
        str.find_first_of("abc", begin, len);

        //size_t find_last_of(const string & str, size_t pos = npos) const noexcept;
        //size_t find_last_of(const char* s, size_t pos = npos) const;
        //size_t find_last_of(const char* s, size_t pos, size_t n) const;
        //size_t find_last_of(char c, size_t pos = npos) const noexcept;

        // string::size_type
        string::size_type pos = str.find(str2);
        // string::npos
        if (pos == string::npos) { }


        //   
        // string substr(size_t pos = 0, size_t len = npos) const;
        // pos             。              0,    0。
        // len        
        str2 = str.substr(begin);
        str2 = str.substr(begin, len);

        // algorithm
        reverse(str.begin(), str.end());    //   

        //      
        string strTrans = "A";
        transform(strTrans.begin(), strTrans.end(), strTrans.begin(), ::toupper);
        transform(strTrans.begin(), strTrans.end(), strTrans.begin(), ::tolower);

        //   
        // c_str()    const char*  ，           
        // const char* string::c_str() const
        const char* strChar = str.c_str();

        // const char* string::data() const
        // data(): c_str()  ，              
        strChar = str.data();

        // size_type copy(_Out_writes_(_Count) _Elem* const _Ptr, size_type _Count, const size_type _Off = 0) const
        char charAry[20] = { 0 };
        str.copy(charAry, len, begin); // begin  ，  len    

        // compare
        //     0,   ASCII        
        //int compare(const basic_string & s) const;
        //int compare(const Ch * p) const;
        //int compare(size_type pos, size_type n, const basic_string & s) const;
        //int compare(size_type pos, size_type n, const basic_string & s, size_type pos2, size_type n2) const;
        //int compare(size_type pos, size_type n, const Ch * p, size_type = npos) const;
        str.compare("abc");

        // to_string
        //            
        //std::string to_string(int value);
        //std::string to_string(long value);
        //std::string to_string(long long value);
        //std::string to_string(unsigned value);
        //std::string to_string(unsigned long value);
        //std::string to_string(unsigned long long value);
        //std::string to_string(float value);
        //std::string to_string(double value);
        //std::string to_string(long double value);
        str = to_string(1);

    }
};