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# What is the fabs() function in C++? Onyejiaku Theophilus Chidalu

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.   ### Overview

The fabs() function in C++ is used to return the absolute value of an argument passed to the function.

The fabs() function is defined in the cmath header file.

Mathematically, it is represented as: $fabs(num) = |num|$

### Syntax

fabs(double num)


### Parameter value

The fabs() function takes a single parameter value which is a number of any type: double, float, or long double.

### Return value

The fabs() function returns the absolute value of the number passed to it as an argument.

### Example 1

Let’s use the fabs() function for double numbers:

#include <iostream>#include <cmath>using namespace std;int main() {  int result1;   int result2;  // for a negative double  double x = -10.25, result;  // for a positve double  double y = 10.25;  result1 = fabs(x);  result2 = fabs(y);  cout << "fabs(" << x << ") = |" << x << "| = " << result1<<endl;  cout << "fabs(" << y << ") = |" << y << "| = " << result2;  return 0;}
Implementing the fabs() function for double numbers

### Code Explanation

• Line 6–7: We create int variables result1 and result2.
• Line 9–11: We create double variables x and y.
• Line 14–15: Using the fabs() function, we take the absolute value of x and y variables and assign the outputs respectively to variables result1 and result2.
• Line 17 & 18: we printed the variables result1 and result2.

### Example 2

Let’s use the fabs() function for float numbers:

#include <iostream>#include <cmath>using namespace std;int main() {  int result1;   int result2;  // for a negative float  float x = -3.5f, result;  // for a positve float  float y = 3.5f;  result1 = fabs(x);  result2 = fabs(y);  cout << "fabs(" << x << ") = |" << x << "| = " << result1<<endl;  cout << "fabs(" << y << ") = |" << y << "| = " << result2;  return 0;}
Implementing the fabs() function for float numbers

### Example 3

Let’s use the fabs() function for long double numbers:

#include <iostream>#include <cmath>using namespace std;int main() {  int result1;   int result2;  // for a negative long double   long double  x = -1.256, result;  // for a positve long double   long double  y = 1.256;  result1 = fabs(x);  result2 = fabs(y);  cout << "fabs(" << x << ") = |" << x << "| = " << result1<<endl;  cout << "fabs(" << y << ") = |" << y << "| = " << result2;  return 0;}
Implementing the fabs() function fo long double numbers

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functions
c++
absolute
communitycreator

CONTRIBUTOR Onyejiaku Theophilus Chidalu

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.   Keep Exploring

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