Modern C++ uses Strings, Wide Strings, and Unicode Strings to support worldwide languages. Strings (std::string) uses char as the character type which means they are ASCII chars and they are an instantiation of the basic_string class template. In C++, there are several typedefs for common character types and one of them is std:string types that are defined in header <string>.
strings are the string class for byte characters represented with string and alphanumeric characters are stored and displayed in string forms. In other terms, string stores the alphanumeric text with 1-byte chars called char. Strings are the instantiation of the basic_string class template that uses char as the character type. In modern C++, simply we can define a string as below,
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std::string str = "This is a String"; |
The string has methods to append, assign, copy, align, replace or operate with other strings. These methods can be used in all string methods with their appropriate syntax. We can access characters with [ ] brackets; we can use at(), front(), and back() methods to add chars to a string.
In this post, you’ll learn how to access a character of an astring, how to use the at() method of strings, and how to use the front() and back() methods in std::string to access characters. By learning these character elements of a c++ string, it will help you build C++ applications with the use of C++ software.
Table of Contents
How Do I access a single character of a String in C++?
Strings are a class contains arrays of characters with useful methods, and we can access, or modify their characters easily. In C++, while string contents are defined between ” and “, characters are defined between ‘ and ‘. We can access characters with [ ] brackets; we can use at(), front() and back() methods to add chars to a string. Let’s see how we access and modify characters of strings.
Accessing a Character of a String with [ ] brackets
This example below shows how we can access to characters of a string by using [ ] brackets,
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#include <iostream> #include <string> int main() { std::string str = "ABCD"; char c; c = str[0]; // set a char to first char of string std::cout << (char)(c) << std::endl; // printing a character std::cout << str[1] << std::endl; // printing character of a string with [ ] getchar(); return 0; } |
and the string outputs will be,
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A B |
as you see in this example we print the first and second characters of the string.
You can access to a Character of a String with the at() method
We can access any character of a string by using at() method. This example below shows how we can access to characters of a string by using at() method,
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#include <iostream> #include <string> int main() { std::string str = "ABCD"; std::cout << str.at(0) << std::endl; // printing character of a string std::cout << str << std::endl; // printing a string str.at(0) = (char)(88); // set first char to 'X' std::cout << str << std::endl; str.at(1) = '-'; // set second char to '-' std::cout << str << std::endl; str.at(3) = str.at(2); // set forth char to third one, copy one char to another index std::cout << str << std::endl; getchar(); return 0; } |
and the string outputs will be,
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A ABCD XBCD X-CD X-CC |
as you see in this example we print the first and second characters of the string.
How to grab a portion of a C++ String with the front() and back() methods
We can easily reach to the first and the last char of a string by using front() and back() methods. This example below shows how we can access to characters of a string by using front() and back() methods,
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#include <iostream> #include <string> int main() { std::string str = "ABCD"; std::cout << str.front() << std::endl; std::cout << str.back() << std::endl; getchar(); return 0; } |
and the string outputs will be,
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A D |
As you see we can easily reach to the first and last char of a string. Sometimes it is important to check first or last char, if it is a number, if it is a question mark, etc.
Note that, these methods above can be used with std::wstring, std::u16string, std::u32string too.
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