C plus plus program to list all Armstrong number?

Answer 1

#include<iostream>

#include<vector>

unsigned count_digits (unsigned num, const unsigned base=10)

{

unsigned count=1;

while (num/=base) ++count;

return count;

}

class number

{

std::vector<unsigned> value;

unsigned base;

public:

number (const unsigned _value, const unsigned _base=10): value {}, base {_base} { *this = _value; }

number& operator= (const unsigned _value);

operator unsigned () const;

bool is_narcissistic () const;

};

number& number::operator= (unsigned _value)

{

unsigned count = count_digits (_value, base);

value.resize (count);

while (count)

{

value[value.size()-count--] = _value%base;

_value/=base;

}

return *this;

}

number::operator unsigned () const

{

unsigned num = 0;

for (unsigned index=0; index<value.size(); ++index)

num += value[index]*static_cast<unsigned>(std::pow (base, index));

return num;

}

bool number::is_narcissistic () const

{

unsigned num = 0;

for (unsigned index=0; index<value.size(); ++index)

num += static_cast<unsigned>(std::pow (value[index], value.size()));

return num == static_cast<unsigned> (*this);

}

unsigned main()

{

const unsigned min=1;

const unsigned max=100;

std::cout << "Narcissistic numbers in the range " << min << " through " << max << ":\n\t";

for (unsigned n=min; n<=max; ++n)

if (number(n).is_narcissistic())

std::cout << n << ' ';

std::cout << '\n' << std::endl;

}

Answer 2

#include <iostream>

#include <math.h> // for std::pow()

unsigned int get_length(unsigned int num,const unsigned int base=10)

{

unsigned int len=1;

while(num && (num/=base))

++len;

return( len );

}

bool is_armstrong(const unsigned int num,const unsigned int base=10)

{

unsigned int len=get_length(num,base);

unsigned int sum=0;

unsigned int tmp=num;

while(tmp)

{

sum+=(unsigned int)std::pow((double)(tmp%base),(double)len);

tmp/=base;

}

return(num==sum);

}

int main()

{

std::cout << "Armstrong series (base 10):";

for(unsigned int num=0; num<=0xffffffff; ++num)

if(is_armstrong(num))

std::cout << " " << num;

std::cout << std::endl;

return(0);

}