Summarizes string of

Luo Gu solution to a problem from https://www.luogu.org/blog/co2021/solution-p1032

1. Read spaces

getline (CIN, A); // can be read into the spaces

2.c_str ()

int main()
{
    char c[20];
    string s = "12345456";
    strcpy_s(c, s.c_str());
    cout << c << endl;
    cout << c[3];
    //printf("%s", s.c_str());
    getchar();
    getchar();
    return 0;
}

int main()
{
    
    string s = "12345456";
    const char *c = s.c_str();
    cout << c << endl;
    cout << c[3];
    //printf("%s", s.c_str());
    getchar();
    getchar();
    return 0;
}

 

3. Insert insert

str.insert (k, str2), inserted in str2 k-th position.

4. Remove erase

str.erase (k, num) delete the k-th character begins num characters.

5. Alternatively replace

str.replace (k, num, str2); starting from the k-th character two characters replaced str2 string.

String S = " 12,345,456 " ; 
s.replace does ( 0 , 2 , " AS " ); 
COUT << S; // result as345456

6.find

str.find (str2) // Returns the string str position of the first occurrence of str2

str.find (str2, k) // k start looking from the position in str str2 appear

rfind is looking backwards, for example: the output of Example 7

int main()
{
    
    string s = "1200345456";
    int k=s.rfind("45");
    cout << k << endl;
    cout << s;
    //printf("%s", s.c_str());
    getchar();
    getchar();
    return 0;
}

 find_first_of (c, k) // front looking back

find_last_of (c, k) // looking from back to front from start to find k, find the character c, find the return, the match fails to return npos

find_first_not_of()

str.find_last_not_of (str2, k) search for a character in str2 not in str, and returns the first location found.

7.substr()

substr (begin, end) // end if omitted, it means to the end

str="sdnsaddfl amsdlk";

str.substr (0,3); // index is from 0 to 3 i.e. sdn

8.