C++ Program string class and its applications?

String is a sequence of characters. In C++ programming language, The strings can be defined in two ways −

C style strings: treats the string as a character array.
String Class in C++
The string class can be used in a C++ program from the library ‘string’. It stores the string as a character array in the memory but shows it as a string object to the user. In C++ there are many methods that support the C++ string class and help in the proper function of the object and increase the efficiency of the code.

Example

Some common string application are found where string are used −

#include <bits/stdc++.h>
using namespace std;
bool charcheck(string str) {
   int l = str.length();
   for (int i = 0; i < l; i++) {
      if (str.at(i) < '0' || str.at(i) > '9')
         return false;
   }
   return true;
}
string replacedotWith20(string str) {
   string replaceby = "%20";
   int n = 0;
   while ((n = str.find(" ", n)) != string::npos ) {
      str.replace(n, 1, replaceby);
      n += replaceby.length();
   }
   return str;
}
int main() {
   string num = "3452i";
   if (charcheck(num))
      cout << "string contains only digit" << endl;
   else
      cout<<"string contains other characters too"<<endl;
   string url = "google com in";
   cout << replacedotWith20(url) << endl;
   return 0;
}