Strings in

About Strings

A string in C++ is a mutable object that represents text as a sequence of characters (letters, digits, punctuation, etc.). Strings are manipulated by calling the string's methods.

Strings Library

In C++ the string type and the associated functions have to be included from the strings library before usage. You can do so by adding #include <string> to the top of your file. They will then populate the std namespace. The string literal uses the double quote character: ".

#include <string>
std::string w_berry_quote{"A well-made sentence, I think, is a thing of beauty."};

Common String Operations

You can use the + operator to concatenate strings:

std::string original_title{"The School of Rock"};
std::string sequel_indicator{"Electric Boogaloo"};
std::string next_movie_title = original_title + " 2: " + sequel_indicator;

To use the strings library, you need to know that it is possible to call a function that belongs to an object. These are called member functions. Later in the syllabus, you will learn more about member functions and the connected class concept.

std::string qualification{"awesome"};
// 1st argument: from the index to the end of the string:
std::string who_is_awesome = qualification.substr(5); 
// => "me"

// 2nd optional argument for the length:
std::string material{"haunted books"};
std::string ghost = material.substr(8, 3);
// => "boo"

The find function is also very useful. It is called as a member function on the string and takes a string as the argument. find returns the zero-indexed position of the first occurrence in the string.

std::string new_release{"apple released a new app!"};
new_release.find("app");
// => 0
new_release.find("!");
// => 24

There is also the to_string function, which can be used to convert integers and float/double values to string. to_string returns a string.

int num{92};
double exponent{0.92e2};
std::string msg{ std::to_string(num) + " can also be written as " + std::to_string(exponent)};
// => 92 can also be written as 92.0000000