<string>

The essence of <string> is a dynamic array, essentially a std::vector<char>, that can conveniently operate text data.

#include <string>
#include <iostream>

int main() {
  std::string s1 = "Hello";
  std::string s2 = s2("World");
  std::string s3 = s1 + " " + s2;
  std::cout << s3 << std::endl;
}

Operations

1. Assignment and append

   
   std::string s = "abc";
   s = "def";
   s += "ghi";
   s.append("jkl"); // Append
   
   

2. Access

   
   char c = s[0];
   char c2 = s.at(0); // Will check the boundary, will trhow std::out_of_range error
   
   

3. Length and Capacity

   
   size_t len = s.size();
   size_t cap = s.capacity();
   bool empty = s.empty();
   s.reserve(100); // Pre assign space
   s.clear(); // Clear context
   
   

4. Insert, Delete, Replace

   
   s.insert(2, "AB");
   s.erase(1, 3);
   s.replace(0, 2, "XY");
   
   

5. Find and Substr

   
   size_t pos = s.find("XY"); // Will return the substring's position, and will throw std::string::npos error is not found
   std::string sub = s.substr(1, 3);
   
   

6. Compare

   
   std::string a = "abc";
   std::string b = "abd";
   
   if (a == b) {
     // Logic...
   }
   
   if (a < b) {
     // Logic...
   }
   
   

7. C Style String

   
   const char* cstr = s.c_str(); // To get the const char* pointer
   char * data = s.data(); // To get the char* pointer (c++17)
   
   

8. Foreach

   
   std::string s = "hello";
   
   for (size_t i = 0; i < s.size(); ++i) {
     std::cout << s[i];
   }
   
   for (char c : s) {
     std::cout << c;
   }
   
   for (auto it = s.begin; it != s.end(); ++it) {
     std::cout << *it;
   }