There are times when we want to use quotes inside a string. For example, suppose we want to print the message I am John "the coder" Doe:
cout << "I am John "the coder" Doe";
You can already see by the text color that we have a problem. C++ recognizes the string to be only I am John .
C++ finds the first quotation mark and interprets that the string starts there. But then, it finds the second quotation mark (after John ) and interprets the string ends there.
Character escaping comes to our rescue!
Escaping characters:
In C++, some characters serve different functions and so cannot be displayed or printed like other characters. These characters are referred to as special characters.
For example, double quotes (") is considered a special character by C++. Its job is to let C++ know when a string declaration starts / ends.
There is a way to print special characters like these in C++, and that is by using the backslash character (\).
When we put \ before a special character, we tell C++:
"Hey, I know this is a special character, but I don't want to use it like that here. I just want to print it like I print any other character."
For example, when putting a \ before a double quote, C++ no longer interprets that as being the end of the string:
cout << "I am John \"the coder\" Doe";
The output of this code is:
I am John "the coder" Doe
Escaping backslash:
Sometimes we might want to print strings that contain character \, such as a file path in your PC:
cout << "C:\Desktop\Games";
This code looks perfectly fine at first sight, but if you run it, it would produce this output:
C:DesktopGames
That's because in C++, \ is also a special character and its main purpose is escaping other characters, not being printed.
So when the interpreter sees \C for example, it supposes that you are trying to escape character C, which is not a special character thus it's already "escaped".
Like any special character, \ can also be escaped by putting another \ in front of it (\\):
cout << "C:\\Desktop\\Games";
The output of this code is:
C:\Desktop\Games
New line character:
Similarly, the escape sequence can be used to make an otherwise printable character serve a special function.
For example, the letter n can be printed normally, but adding a backslash before it (\n) will indicate the start of a new line:
cout << "Hello world!\nWhat a good day for coding!\n";
cout << "Let's have a blast!";
The output of this code is:
Hello world!
What a good day for coding!
Let's have a blast!
Assignment
Follow the Coding Tutorial and let's escape some characters!
Hint
Look at the examples above if you get stuck.
In this lesson, we will explore the concept of escaping characters in C++. This is a fundamental topic in programming that allows us to include special characters in strings without causing syntax errors. Understanding how to escape characters is crucial for handling strings that contain quotes, backslashes, or other special characters.
Before diving into more complex examples, let's understand the basic concept of escaping characters. In C++, certain characters have special meanings, such as the double quote (") and the backslash (\). To include these characters in a string, we use the backslash (\) as an escape character.
For example, to include a double quote inside a string, we use \":
cout << "I am John \"the coder\" Doe";This tells the compiler to treat the double quotes as part of the string rather than as string delimiters.
Let's delve deeper into the key concepts and techniques for escaping characters in C++.
To include double quotes inside a string, use the backslash (\) before the double quote:
cout << "I am John \"the coder\" Doe";This ensures that the double quotes are treated as part of the string.
To include a backslash in a string, use a double backslash (\\):
cout << "C:\\Desktop\\Games";This tells the compiler to treat the backslashes as literal characters.
The new line character (\n) is used to insert a line break in the output:
cout << "Hello world!\nWhat a good day for coding!\n";This will print the text on separate lines.
Let's look at some examples to see how escaping characters can be applied in different contexts.
cout << "She said, \"Hello, World!\"";This will output:
She said, "Hello, World!"cout << "C:\\Users\\John\\Documents";This will output:
C:\Users\John\Documentscout << "Line 1\nLine 2\nLine 3";This will output:
Line 1
Line 2
Line 3When working with escape characters, it's important to avoid common mistakes and follow best practices.
R"( ... )") for complex strings that contain many special characters.For more advanced usage, consider using raw string literals to simplify the inclusion of special characters:
cout << R"(I am John "the coder" Doe)";This allows you to include special characters without escaping them.
Here is a complete example demonstrating the use of escape characters in C++:
#include <iostream>
int main() {
// Escaping double quotes
std::cout << "I am John \"the coder\" Doe" << std::endl;
// Escaping backslashes
std::cout << "C:\\Desktop\\Games" << std::endl;
// New line character
std::cout << "Hello world!\nWhat a good day for coding!\nLet's have a blast!" << std::endl;
return 0;
}When debugging code that involves escape characters, pay close attention to the output to ensure that special characters are correctly handled. Use print statements to verify the contents of strings.
For testing, create test cases that include various special characters and verify that the output matches the expected results.
When approaching problems related to escape characters, break down the problem into smaller parts. Identify which characters need to be escaped and apply the appropriate escape sequences. Practice with different examples to become more comfortable with the concept.
Mastering the use of escape characters in C++ is essential for handling strings that contain special characters. By understanding and applying the concepts covered in this lesson, you will be able to write more robust and error-free code.