How to retain 2 decimal places for output in c++

There are two ways to retain two decimal places in output in C: 1. Use std::fixed and std::setprecision to control the output stream formatting, such as: cout << fixed << setprecision (2) << value; 2. Use std::to_string and std::substr to convert the number to a string and extract the number of decimal places, such as: string result = str.substr(0, str.find('. ') 3);

How to retain two decimal places in C output?

There are two ways to retain two decimal places in output in C:

1. Use std::fixed and std::setprecision

This method is implemented by controlling the formatting of the output stream.

#include <iostream>
#include <iomanip>

using namespace std;

int main() {
  double value = 123.456789;

  // 设置保留两位小数
  cout << fixed << setprecision(2) << value << endl;

  return 0;
}

Output:

<code>123.46</code>

2. Using std::to_string and std::substr

This method involves converting a number to a string, Then extract the required number of decimal places.

#include <iostream>
#include <string>

using namespace std;

int main() {
  double value = 123.456789;

  // 转换为字符串
  string str = to_string(value);

  // 提取两位小数
  string result = str.substr(0, str.find('.') + 3);

  cout << result << endl;

  return 0;
}

Output:

<code>123.46</code>

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