원주율 구하기 프로그램

#include <stdio.h>
#include <conio.h>

#define MAXDIGIT 2503

void divide_longnum_by_int( int x[], int y, int z[] )
{
long dividend;
int quotient;
long remainder;
int i;
remainder = 0;
for (i = 0; i < MAXDIGIT; i++) {
dividend = remainder * 10000L + x[i];
quotient = dividend / y;
remainder = dividend % y;
z[i] = quotient;
}
}

void multiply_longnum_by_int( int x[], int y, int z[] )
{
long sum;
long carry;
int i;

carry = 0;
for (i = MAXDIGIT - 1; i >= 0; i--) {
sum = (long)x[i] * y + carry;
z[i] = sum % 10000;
carry = sum / 10000;
}
}

void add_longnum( int x[], int y[], int z[] )
{
int carry, sum;
int i;
carry = 0;
for (i = MAXDIGIT - 1; i >= 0; i--) {
sum = x[i] + y[i] + carry;
z[i] = sum % 10000;
carry = sum / 10000;
}
}

int longnum_is_zero( int x[] )
{
int i;
for (i = MAXDIGIT - 1; i >= 0; i--) {
if (x[i] != 0)
return 0;
}
return 1;
}

void print_longnum( int x[] )
{
int i, count;

printf("%d.", x[0]);

count = 1;
for (i = 1; i < MAXDIGIT - 2; i++) {
printf("%04d", x[i]);
}
}

void set_longnum_to_int( int x[], int n )
{
int i;

x[0] = n;
for (i = 1; i < MAXDIGIT; i++) {
x[i] = 0;
}
}


int main()
{
int a[MAXDIGIT];
int pi[MAXDIGIT];
int i, j;

clrscr();

set_longnum_to_int( pi, 2 );
set_longnum_to_int( a, 2 );

for (i = 1, j = 3; ! longnum_is_zero( a ); i++, j += 2) {
multiply_longnum_by_int( a, i, a );
divide_longnum_by_int( a, j, a );
add_longnum( pi, a, pi );
}

gotoxy(1, 5);
printf("Value of PI ( %4d digit ) =", MAXDIGIT);
gotoxy(1, 7);
print_longnum( pi );
printf("\n");

getch();

return 0;
}