Formatted Io | Input And Output | Cplusplus Tutorial

Introduction

Formatted I/O in C++ refers to the process of controlling the format of input and output operations. This can include specifying the width of output fields, setting the number of decimal places for floating-point numbers, and aligning text. In this tutorial, we will cover various techniques and functions used to format I/O in C++.

Basic Output Formatting

The most common way to format output in C++ is using the stream manipulators provided by the iostream library. Let's look at some basic examples:

Example:

#include <iostream>
using namespace std;

int main() {
    int num = 123;
    cout << "Default: " << num << endl;
    cout << "Hexadecimal: " << hex << num << endl;
    cout << "Octal: " << oct << num << endl;
    cout << "Decimal: " << dec << num << endl;
    return 0;
}

Default: 123
Hexadecimal: 7b
Octal: 173
Decimal: 123

Setting Field Width

You can set the width of the output field using the setw manipulator from the <iomanip> library.

Example:

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    int num = 123;
    cout << setw(10) << num << endl;
    return 0;
}

Floating-Point Formatting

For floating-point numbers, you can control the precision and format using various manipulators.

Example:

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    double num = 123.456789;
    cout << fixed << setprecision(2) << num << endl;
    cout << scientific << setprecision(2) << num << endl;
    return 0;
}

123.46
1.23e+02

Aligning Text

You can align text to the left or right using the left and right manipulators.

Example:

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    cout << left << setw(10) << "Left" << endl;
    cout << right << setw(10) << "Right" << endl;
    return 0;
}

Left
Right

Customizing Fill Characters

You can customize the fill character used to pad the width of the output field using the setfill manipulator.

Example:

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    cout << setfill('*') << setw(10) << 123 << endl;
    return 0;
}

*******123

Combining Manipulators

You can combine multiple manipulators to achieve complex formatting.

Example:

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    double num = 123.456;
    cout << setfill('-') << setw(10) << right << fixed << setprecision(2) << num << endl;
    return 0;
}

----123.46

Conclusion

Formatted I/O in C++ provides a powerful way to control the appearance of your program's output. By using manipulators, you can set field widths, precision, fill characters, and alignment to display your data in a clear and organized manner.