What is endl in C++?
Endl is a manipulator in C++ that is used to insert a newline character (\n) into the output stream and flush the buffer. It is typically used to end a line of output and ensure that the output is immediately displayed on the console or written to a file.
In C++, the output stream is buffered, which means that the data sent to the output stream is not immediately displayed on the console or written to a file, but is instead stored in a buffer until it is full or until the buffer is manually flushed. By using endl, you can explicitly flush the buffer and ensure that any data in the buffer is immediately displayed or written.
For example, the following code uses endl to print "Hello, World!" on a new line:
#include <iostream>
using namespace std;
int main() {
cout<< "Hello, World!" <<endl;
return 0;
}
Output:
Hello, World!
In addition to inserting a newline character and flushing the output stream buffer, endl also has the side effect of slowing down the output process. This is because flushing the buffer can be a time-consuming operation, particularly if the output is being directed to a file or other slow output device.
While endl is commonly used to end a line of output, it is not always necessary to use it. If you simply want to output a newline character without flushing the buffer, you can use the escape sequence '\n' instead.
For example, the following code outputs "Hello" and "World" on separate lines using the '\n' character:
#include <iostream>
using namespace std;
int main() {
cout<< "Hello\n";
cout<< "World\n";
return 0;
}
Output:
Hello
World
Note that because '\n' does not flush the output buffer, the two lines of output are immediately displayed on the console. In contrast, if we had used endl instead of '\n', the output would have been slower as the buffer would have been flushed after each line of output.
Why do we use endl in C++?
In C++, the endl manipulator is often used to end a line of output and flush the output stream buffer. Here are a few reasons why endl is commonly used in C++:
- Ensuring output is immediately displayed: As mentioned earlier, the output stream is buffered in C++, which means that the data sent to the output stream is not immediately displayed on the console or written to a file, but is instead stored in a buffer until it is full or until the buffer is manually flushed. By using endl, you can explicitly flush the buffer and ensure that any data in the buffer is immediately displayed or written.
- Ensuring correctness when reading from the input stream: In some cases, when reading input from the standard input stream using cin, it is necessary to flush the output buffer before reading from the input stream. This is because any data in the output buffer may still be waiting to be displayed on the console, which can interfere with input operations. By using endl after writing output, you can ensure that the output buffer is flushed before attempting to read input.
- Formatting output: endl is often used to format output by ending a line of text or data. This can be useful for displaying data in a readable format or separating different parts of output.
- Debugging: When debugging code, it can be useful to insert endl statements in order to print the values of variables or other information to the console, which can help with identifying bugs in the code.
Advantages of endl in C++
Some advantages of endl are as follows:
- Platform-independent behaviour: Endl provides platform-independent behaviour for inserting a newline character and flushing the output stream buffer. This means that the same code can be used on different platforms without requiring modifications.
- Compatibility with other output manipulators: Endl can be used in combination with other output manipulators, such as setw, setprecision, and setfill, to format output in a precise and customizable way.
- Compatibility with different types of output streams: Endl can be used with different types of output streams, such as standard output streams, file output streams, and string streams, allowing for greater flexibility in the output process.
- Readability: By using endl to end lines of output, code can be made more readable and easier to understand, particularly for complex output operations.
- Debugging: As mentioned earlier, endl can be useful for debugging code by allowing the programmer to print the values of variables or other information to the console.