Difference between printf/scanf and cout/cin in C++?

One of the key features of C++ is its support for input/output – (I/O) operations, which allow the program to receive input from the user and output information to the user. In C++, there are two main ways to perform I/O operations: using the cin and cout functions or using the scanf and printf functions. The debate over which method is more efficient for input and output in the C++ programming language – using printf scanf and cout cin – has been a topic of discussion among developers for many years. Both methods have their own advantages and disadvantages, and which one is more efficient ultimately depends on the specific scenario and context in which they are used. In this article, we will discuss what those methods are, what are the differences, and which one you should be using in your programs.

What are Cin-Cout and Scanf-Printf?

We know both these methods are for taking inputs from a user and displaying output on the screen. But in order to compare these methods, we need to understand how they work and where they come from. So before we discuss the differences, let us briefly discuss both these methods of doing I/O operations using C++ with examples.

Cin, Cout in C++

cin and cout are standard input and output streams in the C++ programming language. They are part of the C++ standard library and are used for reading data from the standard input device (usually the keyboard) and writing data to the standard output device (usually the console).

cin is an object of the istream class, which is used to extract data from the standard input stream (usually the keyboard). cout is an object of the ostream class, which is used to send data to the standard output stream (usually the screen).

cin and cout are considered to be a user-friendly way of doing input and output in C++ because they are object-oriented and support type-safe input and output. This means that they automatically handle the conversion of data types, making it easier to read and write data in your C++ programs.

Here is a very basic example of how cin and cout can be used in a C++ program:

#include <iostream>

using namespace std;

int main()
{
  int num1, num2;

  cout << "Welcome to the codedamn calculator!" << endl;
  cout << "Enter two numbers: ";
  cin >> num1 >> num2;
  cout << "The sum of the two numbers is: " << num1 + num2 << endl;

  return 0;
}
Code language: C++ (cpp)

In the above example, the cout statement is used to display a welcome message and prompt the user to enter two numbers, which are then read from the keyboard using the cin statement. The cin statement extracts the two numbers from the standard input stream and stores them in the num1 and num2 variables. The cout statement then outputs the sum of the two numbers to the screen.

The above example is also available in a Codedamn Playground for you to modify and run.

Scanf, Printf in C++

scanf and printf are standard input and output functions in the C programming language. They are part of the C standard library and are used for reading data from the standard input device (usually the keyboard) and writing data to the standard output device (usually the screen).

Here is the same example showing how scanf and printf can be used in a C++ program:

#include <stdio.h>

int main()
{
  int num1, num2;
  printf("Welcome to the codedamn calculator!\n");
  printf("Enter two numbers: ");
  scanf("%d %d", &num1, &num2);
  printf("The sum of the two numbers is: %d\n", num1 + num2);

  return 0;
}
Code language: C++ (cpp)

In the above example, the printf statement is used to display a welcome message and prompt the user to enter two numbers, which are then read from the keyboard using the scanf statement. The scanf statement extracts the two numbers from the standard input stream and stores them in the num1 and num2 variables. The printf statement then outputs the sum of the two numbers to the screen.

The above example is also available in a Codedamn Playground for you to modify and run.

Advantages of Cout and Cin over Printf() and Scanf()

cout and cin are part of the C++ standard library and are designed to work seamlessly with the C++ language, including features such as object-oriented programming and exception handling. In contrast, printf and scanf are part of the C standard library and are not designed to work as naturally with the C++ language.

Here are some advantages of using cout and cin over printf and scanf in C++ programs:

• cout and cin can handle whitespace more naturally. For example, cin will skip leading whitespace characters automatically, and cout automatically inserts a space between output values.
• cin can be used to extract values of different types (e.g., int, double, string) from the input stream using the >> operator. In contrast, scanf requires you to use a specific format specifier for each type of value that you want to read. cout can be used to output values of different types (e.g., int, double, string) to the output stream using the << operator.
• printf and scanf have slightly different behavior on different platforms and compilers, which can make it harder to write portable code. In contrast, cout and cin are more consistent across platforms and compilers.

Overall, cout and cin are more powerful and flexible input/output mechanisms than printf and scanf, and they are generally the better choice for input and output in C++ programs. However, there may be cases where printf and scanf are more suitable, such as when you need to read or write large amounts of data and performance is a concern.

Difference between Cin-Cout and Scanf-Printf

Difference between Cin and Scanf?

Let’s talk about some of the differences between cin and scanf. cin uses operator overloading to allow you to input data in a more intuitive and readable way, using the >> operator to extract data from the stream. scanf, on the other hand, uses a formatting string to specify how the data should be read. This formatting string includes placeholders for the data, along with instructions for how to interpret it (e.g. type of data, field width, etc.). You can also see the example of the same when we talked about the methods in detail before.

Difference between Cout and Printf?

One of the main differences between cout and printf is the way they handle the formatting. cout uses operator overloading to allow you to output data in a more intuitive and readable way, using the << operator to insert data into the stream. printf, on the other hand, uses a formatting string to specify how the data should be output. This formatting string includes placeholders for the data, along with instructions for how to format it (e.g. precision for floating point numbers, field width, alignment, etc.). Another difference between cout and printf is that cout is typically slower than printf, because it provides more features and performs additional error checking.

Cin-Cout vs Scanf-Printf

If you do competitive programming in platforms like Codeforces or Codechef, speed plays a big role in choosing which method you would use. Generally, printf and scanf are significantly faster than cin and cout.

Cout vs Printf speed in C++

In general, printf is faster than cout in C++, because printf is a C function that is implemented directly in terms of low-level operations, while cout is a C++ function that provides additional features and performs additional error checking. This means that printf can be more efficient when it comes to formatting and outputting data, especially for simple or repetitive output.

Performance of cin/cout can be slow because they need to keep themselves in sync with the underlying C library. This is essential if both C IO and C++ IO are going to be used.

However, if you plan to only use cin and cout, you can simply disable the syncing operation using the following code before doing any I/O operations:

std::ios::sync_with_stdio(false);
Code language: C++ (cpp)

You can see the use of the code snippet above in the following Codedamn Playground. Click on the click and open the nosync.cpp file to view and run the code to your liking.

After doing this, the syncing bottleneck is removed, and now cin sometimes even performs slightly better than scanf! But the speed difference is subjective and negligible.

Important: When you turn off the sync with stdio using the above code, make sure you either use cin/cout or printf/scanf in the entire program. Mixing these two methods now can cause unexpected errors.

Conclusion

Overall, the choice between using cin and cout or scanf and printf ultimately depends on the specific requirements of your program and the trade-offs that you are willing to make between convenience, efficiency, and functionality. Both cin and cout and scanf and printf are valid methods for input and output in C++. Both methods have their own strengths and weaknesses, and the best choice will vary depending on the context in which they are used. In this article, we looked at what these methods do, the differences between these methods, and which one is more efficient. I hope this article has helped you clear all your doubts regarding these 2 ways of doing I/O operations in C++.

If you have any questions regarding this article or want to talk about anything technology, you can find me on Twitter. Thank you for reading!

FAQs

Are Printf and Scanf faster than cin and cout?

In general, printf and scanf are faster than cin and cout. This is because printf and scanf are based on the C standard library, which is generally faster than the C++ standard library, which cin and cout are part of.

It’s worth noting that there are ways to improve the performance of cin and cout, such as using ios::sync_with_stdio(false) to disable synchronization with the C standard library.

Should I use Cin or Scanf in C++?

cin is the standard input stream in C++ and is generally preferred over scanf for input in C++ programs. cin is part of the C++ standard library and is designed to work seamlessly with the C++ language, including features such as object-oriented programming and exception handling.

Which is faster Cout or Printf?

In general, printf is faster than cout. This is because printf is based on the C standard library, which is generally faster than the C++ standard library, which cout is part of.

However, the difference in performance between printf and cout is usually not significant unless you are performing a large number of output operations. In most cases, the difference in performance will not be noticeable.

Is Scanf faster than Cin in Codeforces?

Yes, in general, scanf will be faster than cin in Codeforces or any other platform, for the reasons we mentioned earlier. But you can achieve similar performance with cin by using the ios::sync_with_stdio(false) statement to disable synchronization with the C standard library.

Can we use Printf() and Scanf() in C++ also?

Yes, you can use printf and scanf in C++ programs. These functions are part of the C standard library, which is included in C++ by default. Therefore, you can use printf and scanf in the same way that you would use them in a C program.