Pi(π) in C++ with Examples

Difficulty Level : Easy
Last Updated : 18 Apr, 2020

In this article, we will discuss some of the mathematical function which is used to derived the value of Pi(π) in C++.

Method 1: Using acos() function:
Approach:

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The value of Π is calculated using acos() function which returns a numeric value between [-Π, Π].
Since using acos(0.0) will return the value for Π/2. Therefore to get the value of Π:
```
double pi = 2*acos(0.0);
```
Now the value obtained from above equation is estimated as:
```
printf("%f\n", pi);
```

Below is the implementation of the above approach:

// C++ program for the above approach
  
#include "bits/stdc++.h"
using namespace std;
  
// Function that prints the
// value of pi
void printValueOfPi()
{
  
    // Find value of pi using
    // acos() function
    double pi = 2 * acos(0.0);
  
    // Print value of pi
    printf("%f\n", pi);
}
  
// Driver Code
int main()
{
    // Function that prints
    // the value of pi
    printValueOfPi();
    return 0;
}

Output:

3.141593

Method 2: Using asin() function:
Approach:

The value of Π is calculated using asin() function which returns a numeric value between [-Π, Π].
Since using asin(1.0) will return the value for Π/2. Therefore to get the value of Π:
```
double pi = 2*asin(1.0);
```
Now the value obtained from above equation is estimated as:
```
printf("%f\n", pi);
```

Below is the implementation of the above approach:

// C++ program for the above approach
  
#include "bits/stdc++.h"
using namespace std;
  
// Function that prints the
// value of pi
void printValueOfPi()
{
  
    // Find value of pi using
    // asin() function
    double pi = 2 * asin(1.0);
  
    // Print value of pi
    printf("%f\n", pi);
}
  
// Driver Code
int main()
{
    // Function that prints
    // the value of pi
    printValueOfPi();
    return 0;
}

Output:

3.141593

Method 3: Using inbuilt constant value define in the “cmath” library:
The value of Pi(π) can directly written using the constant stored in cmath library. The name of the constant is M_PI. Below is the program for printing the value of Pi:

// C++ program for the above approach
#include "cmath"
#include "iostream"
using namespace std;
  
// Function that prints the
// value of pi
void printValueOfPi()
{
    // Print value of pi
    printf("%f\n", M_PI);
}
  
// Driver Code
int main()
{
    // Function that prints
    // the value of pi
    printValueOfPi();
    return 0;
}

Output:

3.141593

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Pi(π) in C++ with Examples