How do you convert digit to word in c?

#include<iOStream>

class expand

{

public:

expand(unsigned long long num):value(num){}

std::ostream& operator()(std::ostream& out)const;

private:

unsigned long long value;

static const char * const units[20];

static const char * const tens[10];

};

const char * const expand::units[20] = {"zero", "one", "two", "three","four","five","six","seven",

"eight","nine", "ten", "eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen",

"eighteen","nineteen"};

const char * const expand::tens[10] = {"", "ten", "twenty", "thirty","forty","fifty","sixty","seventy",

"eighty","ninety"};

std::ostream &operator<< (std::ostream &out, expand number)

{

return(number(out));

}

std::ostream &expand::operator()(std::ostream &out) const

{

const unsigned long long quintillion=1000000000000000000;

const unsigned long long quadrillion=1000000000000000;

const unsigned long long trillion=1000000000000;

const unsigned long long billion=1000000000;

const unsigned long long million=1000000;

const unsigned long long thousand=1000;

const unsigned long long hundred=100;

const unsigned long long twenty=20;

const unsigned long long ten=10;

unsigned long long multiple=quintillion;

unsigned long long remain;

if(value>=thousand)

{

while(multiple>value&&(multiple!=quintillionmultiple!=quadrillion

multiple!=trillionmultiple!=billionmultiple!=millionmultiple!=thousand))

multiple/=1000;

out<<expand(value/multiple);

switch(multiple)

{

case(quintillion):out<<"-quintillion"; break;

case(quadrillion):out<<"-quadrillion"; break;

case(trillion):out<<"-trillion"; break;

case(billion):out<<"-billion"; break;

case(million):out<<"-million";break;

case(thousand):out<<"-thousand";break;

}

if(remain=value%multiple)

{

if(remain<hundred)

out<<"-and";

out<<"-"<<expand(remain);

}

}

else if(value>=hundred)

{

out<<expand(value/hundred)<<"-hundred";

if(remain=value%hundred)

out<<"-and-"<<expand(remain);

}

else if(value>=twenty)

{

out<<tens[value/ten];

if(remain=value%ten)

out<<"-"<<expand(remain);

}

else

out<<units[value];

return(out);

}

int main()

{

for(unsigned long long ull=10000000; ull<100000000; ++ull)

std::cout<<expand(ull)<<std::endl;

return(0);

}