How Can I Precisely Control the Number of Decimal Places When Printing Floating-Point Numbers in C ?

Printing Precision Numbers with C 's I/O Manipulators

In this programming scenario, the goal is to print floating-point numbers with a specific number of decimal places using C 's output manipulator. Let's delve into the solution and examine how it accomplishes this task.

Utilizing the header, we can employ two manipulators to achieve the desired result: std::fixed and std::setprecision. std::fixed controls the representation of floating-point numbers and ensures they are displayed in fixed-point notation. On the other hand, std::setprecision specifies the number of decimal places to be printed.

Here's a practical example to illustrate the usage of these manipulators:

#include <iostream>
#include <iomanip>

int main()
{
    double d = 122.345;

    std::cout << std::fixed;
    std::cout << std::setprecision(2);
    std::cout << d;
}

In this code, std::setprecision(2) sets the output to show two decimal places. The std::fixed manipulator ensures that the number is not displayed in scientific notation. As a result, when the code is executed, it produces the following output:

122.34

This demonstrates how the combination of manipulators, std::fixed and std::setprecision, provides a convenient means to control the formatting and precision of floating-point output in C .

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