https://www.geeksforgeeks.org/top-50-string-coding-problems-for-interviews/
- playing with characters test logic of programmer very well
- understanding of C++ Standard Template Library(STL) also increase
- frequently asked string coding questions in every coding round
- 48 to 57 - Number
- 65 to 90 - uppercase [(s[0]>='a'&&s[0]<='z']
- 97 to 122 - lowercase [(s[0]>='A'&&s[0]<='Z']
- lowercase = lowercase + 32
- toupper:- (char)tolower(s[i]);
- tolower:- (char)toupper(s[i]);
Transform:-
- 
transform(s.begin(), s.end(), s.begin(), ::tolower); 
- 
transform(s.begin(), s.end(), s.begin(), ::toupper); 
- 
Find:- s1.find(s2[i])!=string::npos:- it means <find s2[i] in s1> is present 
- 
token:- stringstream ex: 
 string s = "geeks for geeks"; stringstream ss(s); // Used for breaking words
 string word; // to store individual words
 while (ss >> word)
 cout << word << endl;
- 
next_permutation()