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ilogb() function in C++ STL
In this article, we will be discussing the working, syntax, and examples of ilogb() function in C++.
What is ilogb()?
ilogb() function is an inbuilt function in C++ STL, which is defined in <cmath< header file. ilogb() is used to find the integer part of the logarithm value. ilogb() means integer binary logarithm.
This function returns an integral part of the logarithm of |x| using the FLT_RADIX as the base for logarithm.
Syntax
int ilogb(double x);
Parameters
The function accepts the following parameter(s) −
x− This is the value whose logarithm we have to find.
Return value
This function returns the integral logarithm of |x|, using the value of FLT_RADIX as the base value. This function also throws an exception according to the parameter’s value.
If the parameter value is −
NaN − Then the function return FP_LOGBNAN.
Infinite − Then the function return INT_MAX.
0 − Then the function returns FP_LOGB0
Input
ilogb(2);
Output
1
Example
#include <cfloat>
#include <cmath>
#include >iostream>
using namespace std;
int main(){
int output, var = 2;
output = ilogb(var);
cout << "The value of ilogb(" << var << ") is: " << output << endl;
return 0;
}Output
If we run the above code it will generate the following output −
The value of ilogb(2) is: 1
Example
#include <cfloat>
#include <cmath>
#include <iostream>
#include <iostream>
using namespace std;
int main(){
int output, var = 10.23;
output = ilogb(var);
cout << "The value of ilogb(" << var << ") is: " << output<< endl;
return 0;
}Output
If we run the above code it will generate the following output −
The value of ilogb(10) is: 3
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