C++ Programming Code Examples
C++ > Data Structures and Algorithm Analysis in C++ Code Examples
Recursive exponentiation algorithm, with a test program
/* Recursive exponentiation algorithm, with a test program */
#include <iostream.h>
bool isEven( int n )
{
return n % 2 == 0;
}
long pow( long x, int n )
{
/* 1*/ if( n == 0 )
/* 2*/ return 1;
/* 3*/ if( n == 1 )
/* 4*/ return x;
/* 5*/ if( isEven( n ) )
/* 6*/ return pow( x * x, n / 2 );
else
/* 7*/ return pow( x * x, n / 2 ) * x;
}
/* END */
// Test program
int main( )
{
cout << "2^21 = " << pow( 2, 21 ) << endl;
cout << "2^30 = " << pow( 2, 30 ) << endl;
return 0;
}
#include is a way of including a standard or user-defined file in the program and is mostly written at the beginning of any C/C++ program. This directive is read by the preprocessor and orders it to insert the content of a user-defined or system header file into the following program. These files are mainly imported from an outside source into the current program. The process of importing such files that might be system-defined or user-defined is known as File Inclusion. This type of preprocessor directive tells the compiler to include a file in the source code program.
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