You can control the number of significant digits in your output with the _______

In this post, we will learn about significant figures in C++. Significant, as the name suggests means the number of digits that are actually meaningful to us. For example, the number 2544 has 4 significant figures. C++ supports many types of variables like int, float, char, etc. While using the data types like float and double our answer can have a large number of digits after the decimal point. For example 1/6=0.166666666. Moreover, sometimes we might get an answer that overflows the memory because we are provided with only 4 bytes or 8 bytes of memory depending upon the data type and the size allocated to it.

Inhaltsverzeichnis Show

Significant figures in C++ using setprecision()
What manipulator is used to establish a field width for the value that follows it?
When the fixed manipulator is used the value specified by the Setprecision manipulator will be the number of digits to appear after the decimal point?
What is the difference between the GET function and >> operator?
When a variable is assigned a number that is too large for its data type?

The number of significant figures is a measure of the precision of our answer. This means that when we say our answer has 4 significant figures, we are implying that our answer is precise up to 4 places. The data types follow a hierarchy with respect to the precision they give. Long double is the most precise and float is the least precise among float, double and long double. Typically, the float has 7 significant digits while double has 15 significant digits. Hence, while rounding off a number with more than 7 significant digits float has more error as compared to a double type number. We can set the precision of our answer in C++ according to our needs.

C++ has a library called iomanip which provides us a function named setprecision() using which we can change the number of significant digits.

Significant figures in C++ using setprecision()

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

int main() {
  float num=8.28478; //6 significant figures
  
  cout<<setprecision(1)<<num<<endl;   //1 significant figures
  cout<<setprecision(2)<<num<<endl;   //2 significant figures
  cout<<setprecision(3)<<num<<endl;   //3 significant figures
  cout<<setprecision(4)<<num<<endl;   //4 significant figures
  cout<<setprecision(5)<<num<<endl;   //5 significant figures
  cout<<setprecision(6)<<num<<endl;   //6 significant figures
  
  
  return 0;
}

OUTPUT

The output we are getting helps us to understand the working of the setprecision() function. When we want only 1 significant figure, our number is rounded off to 8 i.e a single digit. Next, if we want our answer to be precise up to 2 places, the number is rounded off to 8.3. In this way, we can manage the number of precise or significant digits we want in our answer.

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1.…are used to translate each source code instructioninto the appropriate machine language instruction