全能万进制高精度模板

#include 
#include 
#include 
#include 
#include 
#include 

using namespace std ;
typedef long long llong ;
const int size = 50000 ;
const int base = 10000 ;   //高精度数字中每一个元素表示数字的几位，100就是2位。1000就是4位。
const int cap = 50000 ;

struct bignum {
    int len ; int data[cap] ;
    bignum():len(0) {}
    bignum( int x ):len(0) {//小整数赋值//
        for( ; x>0; x/=base) data[len++] = x % base ; 
    }
    bignum( const bignum &x ):len(x.len) {//bignum拷贝赋值//
        memcpy( data, x.data, len*sizeof(data[0]) ) ;
    }

    int &operator[]( int posi ) {   //直接定义bignum
        return data[posi] ;
    }
    int operator[]( int posi )const {
        return data[posi] ;
    }
};

int cmp( const bignum &A, const bignum &B )  //比较 两个高精度数的大小 1是A大，-1是B大  0是相等。
{
    if( A.len != B.len ) return A.len > B.len ? 1 : - 1 ;
    int i ; for( i=A.len-1; i>=0&&A[i]==B[i]; i-- ) ;

    if( i < 0 ) return 0 ;//相等//
    return A[i] > B[i] ? 1 : -1 ;
}

bignum operator+( const bignum &A, const bignum &B )
{
    int i ; int carry = 0 ; bignum R ;
    for( i=0; i0; i++ )
    {
        if( i < A.len ) carry += A[i] ;
        if( i < B.len ) carry += B[i] ;
        R[i] = carry % base ; carry = carry / base ;
    }
    R.len = i ;  return R ;
}

bignum operator-( const bignum &A, const bignum &B )
{
    int i ; int carry = 0 ; bignum R ;
    R.len = A.len ;
    for( i=0; i    {
        R[i] = A[i] - carry ; if( i < B.len ) R[i] -= B[i] ;
        if( R[i] < 0 )    { carry = 1 ; R[i] += base ; }
        else carry = 0 ;
    }
    while( R.len>0&&0==R[R.len-1] ) R.len-- ;//消除相减导致的前缀0
    return R ;
}
//高精度乘单精度，单精度必须放在右边
bignum operator*( const bignum &A, const int &B )
{
    int i ; llong carry = 0 ; bignum R ;
    for( i=0; i0; i++ )
    {
        if( i        R[i] = carry % base ; carry = carry / base ;
    }
    R.len = i ;    return R ;
}

bignum operator*( const bignum &A, const bignum &B )
{
    int i,j ; llong carry = 0 ; 
    bignum R ;
    for( i=0; i        for (j=0;j        {
            carry = (llong)(A[i])*B[j] +R[i+j]; 
            R[i+j] = carry % base ;  //这两步运算可以防止爆掉。
            R[i+j+1] += carry / base ; ;
        }
    R.len = i+j-1 ;   
    while (R[R.len]) R.len++;
	while (!R[R.len-1]) R.len--;
    return R ;
}

bignum operator/( const bignum &A, const int &B )
{
    int i ; llong carry = 0 ; bignum R ;
    for( i=A.len-1; i>=0; i-- )
    {
        carry += A[i] ;
        R[i] = carry / B ; 
        carry = carry - R[i]*B ; carry = carry * base ;
    }
    R.len = A.len ; while( R.len>0&&0==R[R.len-1] ) R.len-- ;//消除前缀0

    return R ;
}
llong mod( const bignum &A, const int &B )
{
    int i ; llong carry = 0 ;
    for( i=A.len-1; i>=1; i-- )
    {
        carry += A[i] ; carry = carry % B ; carry *= base ;
    }
    carry = carry + A[i] ; carry = carry % B ;
    return carry ;
}

istream &operator>>( istream &in, bignum &x )
{
    char ch ;
    for( x=0; in>>ch; )
    {
        x = x*10 + (ch-'0') ;
        if( in.peek() <= ' ' ) break ;//注意是空格，表明以空格作为数的间隔。//
    }
    return in ;
}
ostream &operator<<( ostream &out, const bignum &x )
{
    out << ( 0==x.len ? 0 : x[x.len-1] ) ;  //首位不需要补0
    for( int i=x.len-2; i>=0; i-- )  // 
        for( int j=base/10; j>0; j/=10 ) //如果不够base位，需要补0.所以一位一位输出。
            out << x[i]/j%10 ;

    return out ;
}
void mytostr( string &str, const bignum &x )
{
    str.clear() ; char temp[15] ;
    if( 0 == x.len ) str += '0' ;
    else
    {
        sprintf( temp, "%d", x[x.len-1] ) ;
        str += temp ;
    }
    for( int i=x.len-2; i>=0; i-- )
        for( int j=base/10; j>0; j/=10 )
            str += char(x[i]/j%10+'0') ;
    str.reserve() ;
}

int main()  
{
	bignum a,b,c;
	 cin>>a;
	 cin>>b;
	c=a*b;
	 cout<  return 0 ;
}