String

alphbet order

ASCII Code: 0(48) < 1 < .... < 9(57)

ASCII Code: A(65) < B < .... < Z(90) < a(97) < b < .... < z(122)

isalpha

checks whether char is an alphabetic letter. Return true or false.

isalnum

Checks whether char is either a decimal digit or an uppercase or lowercase letter. Return true or false.

isdigit

checks whether char is decimal digit charachter. Return true or false.

toupper

make each charachter uppercase in the string

tolower

make each charachter lowercase in the string

substr

str.substr(position, length)

find

str.find(target) == -1 means the target string doesn't exist in the str.

Stringstream

Extracts characters from ss and stores them into str s until the delimitation character delim is found (or the newline character, '\n', if there is no delimiter parameter).

getline(string ss, string s)

getline(string ss, string s, char delimiter)

ss : istream object from which characters are extracted.

s : string object where the extracted line is stored.

// extract to string #include <iostream> #include <sstream> #include <string> using namespace std; int main () { string contents = "Please, enter your full name: "; stringstream ss(contents); string s; while(getline (ss ,s, ' ')) cout << s << "\n"; return 0; }

[Hard] No.588 Design In-Memory File System

class FileSystem { struct node { bool isFile; map<string, node*> next; string content; //initialize node() { isFile = false; } }; node *root; public: FileSystem() { root = new node(); } vector<string> ls(string path) { stringstream ss(path); string s; node *iter = root; while(getline(ss, s, '/')) { if(s.size() == 0) continue; iter = iter->next[s]; } if(iter->isFile) return vector<string>{s}; vector<string> ret; for(auto it : iter->next) ret.push_back(it.first); return ret; } void mkdir(string path) { stringstream ss(path); string s; node *t = root; while(getline(ss, s, '/')) { if(s.size() == 0) continue; if(t->next.count(s) == 0) { t->next[s] = new node(); } t = t->next[s]; } } void addContentToFile(string filePath, string content) { stringstream ss(filePath); string s; node *t = root; while(getline(ss, s, '/')) { if(s.size() == 0) continue; if(t->next.count(s) == 0) t->next[s] = new node(); t = t->next[s]; } t->isFile = true; t->content = t->content.size() == 0 ? content : t->content += content; } string readContentFromFile(string filePath) { stringstream ss(filePath); string s; node *t = root; while(getline(ss, s, '/')) { if(s.size() == 0) continue; t = t->next[s]; } return t->content; } };