how to declare a string c 2b 2b

1std::string str = "hello world"; 
2char *str = "hello world";
3char str[] = "hello world"; 
4char str[11] = "hello world"; 

1#include <string>
2#include <iostream>
3#include <type_traits>
4#include <cstring>
5
6int main() {
7  std::string str = "Hello, there";
8  std::cout << std::boolalpha
9  << str.capacity() << ", " << str.size() << ", " << std::strlen(str.data()) // 12, 12, 12
10  << '\n' << std::is_same_v<std::string, std::basic_string<char>> // true
11  << '\n' << str.front() + str.substr(1, 10) + str.back() // Hello there
12  << '\n' << str[0] // H
13  << '\n';
14  
15  str += "!"; 
16  std::cout << str << '\n'; // Hello, there!
17  str.erase(4, 4); // Hellhere!
18  str.pop_back(); // Hellhere
19  str.insert(4, " "); // Hell here
20  std::cout << str << '\n'; // Hell here
21  
22}

1#include <iostream>
2#include <string>//for printing std::string
3int main()
4
5{
6	//A string is a group of characters and an array of const chars
7	const char* name = "Caleb";//C style string
8	//how string actually works below:
9	//String without null terminating character below:
10
11	char name2[5] = { 'C','a','l','e','b' };// string is just an array of characters
12	//The above doesn't have an null termination character at the end cout will not now where the string ends and will acess memory that is not a part of your string
13	std::cout << name2 << std::endl;//output => Caleb + somejunk //this is because null terminating char is not present at the end of array
14	//String with null terminating character below:
15
16	char name3[6] = { 'C','a','l','e','b','\0' };//null terminating char '\0' or '0' can be used 
17	std::cout << name3 << std::endl;//output => Caleb // because null terminating char is present cout knows where array ends 
18
19	//std::string class in c++ is takes an array of const chars and a bunch of functions to manuplate it:
20	//std::string has a constructor  that takes const char array
21	std::string name4 = "Caleb";
22	name4.size();//gives size of string and there are many more methods in std::string class
23	
24  //appending to std::string
25  
26  	//"Ever thing inside these double quotes becomes const char array"
27   //std::string namee = "Caleb" +"Hello";//This will give error because adding const char array to const char array 
28	std::string namee = "Caleb";
29	namee += " Hello";//This will work because adding a ptr to a actual string
30	std::cout << namee << std::endl;
31//You can also use the below
32	std::string namee2 = std::string("Caleb")+" Hello";// This will work because constructor will convert const char array  to string, adding a ptr to string
33	std::cout << namee2 << std::endl;
34    std::cin.get();
35
36}

1#include <string>
2
3std::string myString = "Hello, World!";

1
2  // Include the string library
3#include <string>
4
5// Create a string variable
6std::string greeting = "Hello"; 

1printf("%s\n",someString.c_str());