String Formatting

String formatting allows you to control the appearance of strings when they are printed or displayed. In C++, you can use the std::cout object along with formatting manipulators to format strings.

One common use case for string formatting is to control the number of decimal places when printing floating-point numbers. For example, if you have a variable pi with the value 3.14159265359 and you want to display it with 2 decimal places, you can use the std::fixed and std::setprecision manipulators from the <iomanip> header. Here's an example:

1#include <iostream>
2#include <iomanip>
3
4int main() {
5  double pi = 3.14159265359;
6
7  // Format pi to display with 2 decimal places
8  std::cout << "Pi: " << std::fixed << std::setprecision(2) << pi << std::endl;
9
10  return 0;
11}

In this example, we start with a variable pi with the value of 3.14159265359. We use the std::cout object to display the string "Pi: " followed by the formatted value of pi. The std::fixed manipulator ensures that the number is displayed in fixed-point notation, and the std::setprecision manipulator sets the precision (number of decimal places) to 2.

The output of the code will be:

1Pi: 3.14

String formatting in C++ provides various other manipulators and options to control the appearance of strings, such as setting the width, alignment, padding, and more. You can explore the <iomanip> header for more information and options.

xxxxxxxxxx

#include <iostream>

#include <iomanip>

​

int main() {

  double pi = 3.14159265359;

​

  // Format pi to display with 2 decimal places

  std::cout << "Pi: " << std::fixed << std::setprecision(2) << pi << std::endl;

​

  return 0;

}