C++ 程序设计 OJ2 - 参考答案 MASTER 2019 年 5 月 4 日

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1 C++ 程序设计 OJ2 - 参考答案 MASTER 2019 年 5 月 4 日 1

2 1 RATIONAL 1 Rational 题目描述 设计一个有理数类 Rational, 要求对运算符 + - * / 和 += -= *= /= 进行重载, 完成有理数的加减乘除以及加减乘除复合赋值运算 ; 并且重载 << 和 >> 操作符完成有理数的输入和输出 最后, 重载 == 和!= 比较两个有理数是否相等 使用以下的 main 函数体进行测试 : int main() { Rational r1, r2; while (cin >> r1 >> r2) { cout << "r1 = " << r1 << "\n" << "r2 = " << r2 << endl; cout << "r1+r2 = " << r1 + r2 << endl; cout << "r1-r2 = " << r1 - r2 << endl; cout << "r1*r2 = " << r1 * r2 << endl; cout << "r1/r2 = " << r1 / r2 << endl; } cout << (r1 == r2) << " " << (r1!= r2) << endl; cout << (r1 += r2) << endl; cout << (r1 -= r2) << endl; cout << (r1 *= r2) << endl; cout << (r1 /= r2) << endl; } return 0; 输入 输入 r1,r2 的值 输出 输出 r1,r2 在各种操作之后的值 样例输入 样例输出 r1 = -2/3 r2 = -2/5 r1+r2 = -16/15 r1-r2 = -4/15 r1*r2 = 4/15 r1/r2 = 5/ /15-2/3 4/15-2/3 注意 2

3 1 RATIONAL 1 #include <iostream > 2 #i n c l u d e <iostream > 3 using namespace std ; 4 5 c l a s s Rational 6 { 7 p u b l i c : 8 Rational ( i n t numerator =0, i n t denominator=1) ; 9 10 Rational o p e r a t or+( const Rational &b ) const ; 11 Rational operator ( const Rational &b ) const ; 12 Rational o p e r a t or *( const Rational &b ) const ; 13 Rational o p e r a t or /( const Rational &b ) const ; Rational o p e r a t or+=(const Rational &b ) ; 16 Rational operator =(const Rational &b ) ; 17 Rational o p e r a t or *=( const Rational &b ) ; 18 Rational o p e r a t or /=( const Rational &b ) ; bool o p e r a t o r==(const Rational &b ) const ; 21 bool o p e r a t o r!=( const Rational &b ) const ; void Normalize ( ) ; // 化简 f r i e n d std : : ostream& operator <<(std : : ostream &os, const Rational &r ) ; 26 f r i e n d std : : istream& operator >>(std : : istream &i s, Rational &r ) ; 27 p r i v a t e : 28 i n t numerator, denominator ; // 分子, 分母 29 } ; Rational : : Rational ( i n t numerator, i n t denominator ) 33 { 34 t h i s >numerator = numerator ; 35 t h i s >denominator = denominator ; 36 Normalize ( ) ; 37 } // 最大公约数, 辗转相除法 40 i n t gcd ( i n t x, i n t y ) 41 { 42 return y > 0? gcd ( y, x % y ) : x ; 43 } // 化简 先求出最大公约数 g, 然后分子分母除以 g 3

4 1 RATIONAL 46 void Rational : : Normalize ( ) 47 { 48 i f ( denominator < 0) 49 {// 保证分母为正 50 numerator = numerator ; 51 denominator = denominator ; 52 } i n t g = gcd ( abs ( numerator ), denominator ) ; 55 numerator /= g, denominator /= g ; 56 } Rational Rational : : operator+( const Rational &b ) const 59 { 60 Rational r e s ( numerator *b. denominator + denominator *b. numerator, denominator *b. denominator ) ; 61 return r e s ; 62 } Rational Rational : : operator ( const Rational &b ) const 65 { 66 Rational r e s ( numerator *b. denominator denominator *b. numerator, denominator *b. denominator ) ; 67 return r e s ; 68 } Rational Rational : : operator *( const Rational &b ) const 71 { 72 Rational r e s ( numerator *b. numerator, denominator *b. denominator ) ; 73 return r e s ; 74 } Rational Rational : : operator /( const Rational &b ) const 77 { 78 Rational r e s ( numerator *b. denominator, denominator *b. numerator ) ; 79 return r e s ; 80 } Rational Rational : : operator+=(const Rational &b ) 83 { 84 Rational r e s ( numerator *b. denominator + denominator *b. numerator, denominator *b. denominator ) ; 85 * t h i s = r e s ; 86 return r e s ; 87 } 4

5 1 RATIONAL Rational Rational : : operator =(const Rational &b ) 90 { 91 Rational r e s ( numerator *b. denominator denominator *b. numerator, denominator *b. denominator ) ; 92 * t h i s = r e s ; 93 return r e s ; 94 } Rational Rational : : operator *=( const Rational &b ) 97 { 98 Rational r e s ( numerator *b. numerator, denominator *b. denominator ) ; 99 * t h i s = r e s ; 100 return r e s ; 101 } Rational Rational : : o p e r a t o r /=( const Rational &b ) 104 { 105 Rational r e s ( numerator *b. denominator, denominator *b. numerator ) ; 106 * t h i s = r e s ; 107 return r e s ; 108 } bool Rational : : o p e r a t o r==(const Rational &b ) const 111 { 112 return ( t h i s >numerator * b. denominator == t h i s >denominator * b. numerator ) ; 113 } bool Rational : : o p e r a t o r!=( const Rational &b ) const 116 { 117 return ( t h i s >numerator * b. denominator!= t h i s >denominator * b. numerator ) ; 118 } std : : ostream& operator <<(std : : ostream &os, const Rational &r ) 122 { 123 os << r. numerator << "/" << r. denominator ; 124 return os ; 125 } std : : istream& o p e r a t o r >> ( std : : istream &i s, Rational &r ) 128 { 129 i s >> r. numerator >> r. denominator ; 5

6 1 RATIONAL 130 r. Normalize ( ) ; 131 return i s ; 132 } void Test ( ) 136 { 137 Rational c ( 0, 12) ; 138 cout << c << endl ; Rational c1 ( 3, 12), c2 ( 5, 15), c3 ; 141 c3 = c1 + c2 ; 142 cout << c3 << endl ; 143 return ; 144 } i n t main ( ) 147 { 148 Rational r1, r2 ; 149 while ( c i n >> r1 >> r2 ) 150 { 151 cout << "r1 = " << r1 << "\n" << "r2 = " << r2 << endl ; cout << "r1+r2 = " << r1 + r2 << endl ; 154 cout << "r1-r2 = " << r1 r2 << endl ; 155 cout << "r1*r2 = " << r1 * r2 << endl ; 156 cout << "r1/r2 = " << r1 / r2 << endl ; cout << ( r1 == r2 ) << " " << ( r1!= r2 ) << endl ; 159 cout << ( r1 += r2 ) << endl ; 160 cout << ( r1 = r2 ) << endl ; 161 cout << ( r1 *= r2 ) << endl ; 162 cout << ( r1 /= r2 ) << endl ; 163 } return 0 ; 166 } 6

7 2 CHECKEDPTR 2 CheckedPtr 题目描述 自增 (++) 和自减 (--) 操作符经常由诸如迭代器这样的类实现, 这样的类提供类似于指针的行为访问序列中的元素 例如, 可以定义一个类, 该类指向一个数组并为该数组中的元素提供访问检查 假设, 有以下类, 它将处理 int 数组 class CheckedPtr{ public: CheckedPtr(int * b, int * e) : begin(b), end(e), current(b){ } CheckedPtr & operator ++(); // prefix ++ CheckedPtr & operator --(); // prefix -- CheckedPtr operator ++(int); // postfix ++ CheckedPtr operator --(int); // postfix -- int* Begin(); int* End(); int* Current(); private: int *begin; //pointer to beginning of the array int *end; //one past the end of the array int *current; //current position within the array }; 实现这个类并使用以下 main 函数测试此类 int main() { int array[10] = {1,2,3,4,5,6,7,8,9,10}; CheckedPtr cp(array, array+sizeof(array)/sizeof(array[0])); for(; cp.current()<cp.end(); cp++) cout<<*cp.current()<<" "; cout<<endl; for(--cp; cp.current()>cp.begin(); cp--) cout<<*cp.current()<<" "; cout<<*cp.current()<<endl; } return 0; 输入 无 输出 样例输入 null 样例输出

8 2 CHECKEDPTR 1 #i n c l u d e <iostream > 2 using namespace std ; 3 4 c l a s s CheckedPtr { 5 p u b l i c : 6 CheckedPtr ( i n t * b, i n t * e ) : begin ( b ), end ( e ), c u r r e n t ( b ) { 7 } 8 CheckedPtr & o p e r a t o r ++() ; // p r e f i x ++ 9 CheckedPtr & o p e r a t o r () ; // p r e f i x 10 CheckedPtr operator ++(i n t ) ; // p o s t f i x CheckedPtr operator (i n t ) ; // p o s t f i x 12 i n t * Begin ( ) ; 13 i n t * End ( ) ; 14 i n t * Current ( ) ; 15 p r i v a t e : 16 i n t * begin ; // p o i n t e r to b e g i n n i n g o f the array 17 i n t *end ; // one p a s t the end o f the array 18 i n t * c u r r e n t ; // current p o s i t i o n w i t h i n the array 19 } ; CheckedPtr & CheckedPtr : : o perator ++(){ 22 i f ( c u r r e n t == end ) 23 cout<<" increment past the end of CheckedPtr."<<e n d l ; 24 e l s e 25 ++c u r r e n t ; 26 return * t h i s ; 27 } CheckedPtr & CheckedPtr : : o perator (){ 30 i f ( c u r r e n t == begin ) 31 cout<<" decrement past the beginning of CheckedPtr."<<e n d l ; 32 e l s e 33 c u r r e n t ; 34 return * t h i s ; 35 } CheckedPtr CheckedPtr : : operator ++(i n t ) { 38 CheckedPtr r e t (* t h i s ) ; 39 ++*t h i s ; // 调用 p r e f i x return r e t ; 41 } CheckedPtr CheckedPtr : : operator (i n t ) { 44 CheckedPtr r e t (* t h i s ) ; 45 *t h i s ; // 调用 p r e f i x 8

9 2 CHECKEDPTR 46 return r e t ; 47 } i n t * CheckedPtr : : Begin ( ) { 50 return begin ; 51 } i n t * CheckedPtr : : End ( ) { 54 return end ; 55 } i n t * CheckedPtr : : Current ( ) { 58 return c u r r e n t ; 59 } i n t main ( ) 62 { 63 i n t array [ 1 0 ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 1 0 } ; 64 CheckedPtr cp ( array, array+s i z e o f ( array ) / s i z e o f ( array [ 0 ] ) ) ; 65 f o r ( ; cp. Current ( )<cp. End ( ) ; cp++) 66 cout <<*cp. Current ( )<<" " ; 67 cout<<endl ; f o r ( cp ; cp. Current ( )>cp. Begin ( ) ; cp ) 70 cout <<*cp. Current ( )<<" " ; 71 cout<<*cp. Current ( )<<endl ; return 0 ; 74 } 9

10 3 STRING 3 String 题目描述 实现以下 String 类并测试这个类 class String{ private: char * s; public: String(); String(const char *); String(const String &); ~String(); String & operator=(const char *); String & operator=(const String &); String operator+(const char *); String operator+(const String &); String & operator+=(const char *); String & operator+=(const String &); friend istream & operator>>(istream &, String &); friend ostream & operator<<(ostream &, const String &); friend bool operator==(const String &, const char *); friend bool operator==(const String &, const String &); friend bool operator!=(const String &, const char *); friend bool operator!=(const String &, const String &); }; 使用以下的 main 函数进行测试 : int main() { String s; s += "hello"; cout << s << endl; String s1("string1"); String s2("copy of "); s2 += "String1"; cout << s1 << "\n" << s2 << endl; String s3; cin >> s3; cout << s3 << endl; String s4("string4"), s5(s4); cout << (s5 == s4) << endl; cout << (s5!= s4) << endl; String s6("end of "), s7("my string."); s6 += s7; cout << s6 << endl; return 0; } 输入 s3 的值 输出 一连串 String 类的字符串, 详见样例 样例输入 String3 样例输出 hello String1 copy of String1 String3 1 0 End of my string. 10

11 3 STRING 1 #d e f i n e _CRT_SECURE_NO_WARNINGS 2 3 #include <iostream > 4 #include <c s t r i n g > 5 #include <c s t d l i b > 6 using namespace std ; 7 8 c l a s s S t r i n g { 9 p r i v a t e : 10 char * s ; 11 p u b l i c : 12 S t r i n g ( ) ; 13 S t r i n g ( const char *) ; 14 S t r i n g ( const S t r i n g &) ; 15 ~ S t r i n g ( ) ; 16 S t r i n g & o p e r a t or=( const char *) ; 17 S t r i n g & o p e r a t or=( const S t r i n g &) ; 18 S t r i n g o p e r a t or+( const char *) ; 19 S t r i n g o p e r a t or+( const S t r i n g &) ; 20 S t r i n g & o p e r a t or+=(const char *) ; 21 S t r i n g & o p e r a t or+=(const S t r i n g &) ; 22 f r i e n d istream & operator >>(istream &, S t r i n g &) ; 23 f r i e n d ostream & operator <<(ostream &, const S t r i n g &) ; 24 f r i e n d bool o p erator==(const S t r i n g &, const char *) ; 25 f r i e n d bool o p erator==(const S t r i n g &, const S t r i n g &) ; 26 f r i e n d bool o p erator!=( const S t r i n g &, const char *) ; 27 f r i e n d bool o p erator!=( const S t r i n g &, const S t r i n g &) ; 28 } ; S t r i n g : : S t r i n g ( ) { 31 s = new char [ 1 ] ; 32 s [ 0 ] = '\0' ; 33 } S t r i n g : : S t r i n g ( const char * sp ) { 36 s = new char [ s t r l e n ( sp ) + 1 ] ; 37 s t r c p y ( s, sp ) ; 38 } S t r i n g : : S t r i n g ( const S t r i n g & s t r ) { 41 s = new char [ s t r l e n ( s t r. s ) + 1 ] ; 42 s t r c p y ( s, s t r. s ) ; 43 } S t r i n g : : ~ S t r i n g ( ) { d e l e t e [ ] s ; } 11

12 3 STRING S t r i n g & S t r i n g : : operator=( const char * sp ) { 48 d e l e t e [ ] s ; 49 s = new char [ s t r l e n ( sp ) + 1 ] ; 50 s t r c p y ( s, sp ) ; 51 return * t h i s ; 52 } S t r i n g & S t r i n g : : operator=( const S t r i n g & s t r ) { 55 i f ( t h i s!= &s t r ) 56 * t h i s = s t r. s ; 57 return * t h i s ; 58 } S t r i n g S t r i n g : : o p erator+( const char * sp ) { 61 S t r i n g temp ; 62 temp. s = new char [ s t r l e n ( s ) + s t r l e n ( sp ) + 1 ] ; 63 s t r c p y ( temp. s, s ) ; 64 s t r c a t ( temp. s, sp ) ; 65 return temp ; 66 } S t r i n g S t r i n g : : o p erator+( const S t r i n g & s t r ) { 69 S t r i n g temp ; 70 temp = * t h i s + s t r. s ; 71 return temp ; 72 } S t r i n g & S t r i n g : : operator+=(const char * sp ) { 75 return * t h i s = * t h i s + sp ; 76 } S t r i n g & S t r i n g : : operator+=(const S t r i n g & s t r ) { 79 return * t h i s = * t h i s + s t r ; 80 } istream & operator >>(istream & i s, S t r i n g & s t r ) { 84 char temp [ ] ; 85 i s >> temp ; 86 s t r = temp ; 87 return i s ; 88 } ostream & operator <<(ostream & os, const S t r i n g & s t r ) { 12

13 3 STRING 91 os << s t r. s ; 92 return os ; 93 } bool operator==(const S t r i n g & str, const char * sp ) { 96 return strcmp ( s t r. s, sp ) == 0 ; 97 } bool operator==(const S t r i n g & str1, const S t r i n g & s t r 2 ) { 100 return strcmp ( s t r 1. s, s t r 2. s ) == 0 ; 101 } bool operator!=( const S t r i n g & str, const char * sp ) { 104 return strcmp ( s t r. s, sp )!= 0 ; 105 } bool operator!=( const S t r i n g & str1, const S t r i n g & s t r 2 ) { 108 return strcmp ( s t r 1. s, s t r 2. s )!= 0 ; 109 } i n t main ( ) 112 { 113 S t r i n g s ; 114 s += "hello" ; 115 cout << s << endl ; 116 S t r i n g s1 ( "String1" ) ; 117 S t r i n g s2 ( "copy of " ) ; 118 s2 += "String1" ; 119 cout << s1 << "\n" << s2 << endl ; 120 S t r i n g s3 ; 121 c i n >> s3 ; 122 cout << s3 << endl ; 123 S t r i n g s4 ( "String4" ), s5 ( s4 ) ; 124 cout << ( s5 == s4 ) << endl ; 125 cout << ( s5!= s4 ) << endl ; 126 S t r i n g s6 ( "End of " ), s7 ( "my string." ) ; 127 s6 += s7 ; 128 cout << s6 << endl ; 129 return 0 ; 130 } 13

14 4 BIGINT 4 BigInt 题目描述 编写高精度运算类 Bign, 完成大整数的运算, 类的数据成员有两个, 一个是 int 型数据用来存储大数数据的有效长度, 另一个是整型数组用来存储大整数 要求支持字符串赋值和整数赋值, 重载 + - * / >> << += > < >= <= ==!= 等运算符 使用如下 main 函数测试你的程序 int main() { UnsignedBigInt a, b, c; a = " "; c = ; cout << c << endl; while(cin >> b) { cout << a + b << endl; cout << a - b << endl; cout << (a < b) << endl; a += b; cout << a << endl; } return 0; } 输入 一个大整数 输出 用以上 main 函数输出的结果 样例输入 样例输出

15 4 BIGINT 1 #include <s t d i o. h> 2 #i n c l u d e <s t r i n g > 3 #include <iostream > 4 using namespace std ; 5 6 #i n c l u d e <iostream > 7 #include <s t r i n g > 8 #include <vector > 9 10 c l a s s UnsignedBigInt 11 { 12 f r i e n d std : : istream& o perator >> ( std : : istream &i s, UnsignedBigInt & b i g i n t ) ; 13 f r i e n d std : : ostream& operator <<(std : : ostream &os, const UnsignedBigInt &b i g i n t ) ; 14 f r i e n d UnsignedBigInt ADD( const UnsignedBigInt &a, const UnsignedBigInt & b ) 15 { 16 unsigned i n t n = a. b i t s. s i z e ( ) > b. b i t s. s i z e ( )? a. b i t s. s i z e ( ) : b. b i t s. s i z e ( ) ; UnsignedBigInt r e s u l t ; 19 r e s u l t. b i t s. c l e a r ( ) ; 20 i n t c = 0 ; 21 f o r ( unsigned i n t i = 0 ; i < n ; ++i ) 22 { 23 i n t sum = c ; 24 i f ( i < a. b i t s. s i z e ( ) ) sum += a. b i t s [ i ] ; 25 i f ( i < b. b i t s. s i z e ( ) ) sum += b. b i t s [ i ] ; c = sum / 1 0 ; 28 r e s u l t. b i t s. push_back (sum % 10) ; 29 } 30 i f ( c ) 31 r e s u l t. b i t s. push_back ( c ) ; 32 return r e s u l t ; 33 } 34 f r i e n d UnsignedBigInt SUB( const UnsignedBigInt &a, const UnsignedBigInt & b ) 35 { 36 unsigned i n t n = b. b i t s. s i z e ( ) ; 37 unsigned i n t m = a. b i t s. s i z e ( ) ; UnsignedBigInt r e s u l t ; 40 r e s u l t. b i t s. c l e a r ( ) ; 15

16 4 BIGINT 41 i n t c = 0 ; 42 f o r ( unsigned i n t i = 0 ; i < n ; ++i ) 43 { 44 i n t sum = c ; 45 sum += a. b i t s [ i ] ; 46 sum = b. b i t s [ i ] ; i f (sum < 0) 49 { 50 r e s u l t. b i t s. push_back (sum + 10) ; 51 c = 1; 52 } 53 e l s e 54 { 55 r e s u l t. b i t s. push_back (sum) ; 56 } 57 } f o r ( unsigned i n t i = n ; i < m; ++i ) 60 { 61 i n t sum = c ; 62 sum += a. b i t s [ i ] ; i f (sum < 0) 65 { 66 r e s u l t. b i t s. push_back (sum + 10) ; 67 c = 1; 68 } 69 e l s e 70 { 71 r e s u l t. b i t s. push_back (sum) ; 72 c = 0 ; 73 } 74 } while ( r e s u l t. b i t s. back ( ) == 0) r e s u l t. b i t s. pop_back ( ) ; return r e s u l t ; 79 } 80 f r i e n d bool LESS( const UnsignedBigInt & num, const UnsignedBigInt & other ) 81 { 82 i f (num. b i t s. s i z e ( )!= other. b i t s. s i z e ( ) ) 83 return num. b i t s. s i z e ( ) < other. b i t s. s i z e ( ) ; 84 16

17 4 BIGINT 85 f o r ( unsigned i n t i = num. b i t s. s i z e ( ) 1 ; i >= 0 ; i ) 86 { 87 i f (num. b i t s [ i ]!= other. b i t s [ i ] ) 88 return num. b i t s [ i ] < other. b i t s [ i ] ; 89 } 90 return f a l s e ; 91 } 92 p u b l i c : 93 UnsignedBigInt ( void ) ; 94 UnsignedBigInt ( const std : : s t r i n g s t r ) ; UnsignedBigInt operator=( const std : : s t r i n g s t r ) ; 97 UnsignedBigInt operator=( const char * s t r ) ; 98 UnsignedBigInt operator=( i n t numer ) ; UnsignedBigInt o p e r a t o r +( const UnsignedBigInt &other ) const ; 101 UnsignedBigInt o p e r a t o r+=(const UnsignedBigInt &other ) ; 102 UnsignedBigInt operator ( const UnsignedBigInt &other ) const ; bool operator <( const UnsignedBigInt &other ) const ; 105 bool operator >( const UnsignedBigInt &other ) const ; 106 bool o p e r a t o r==(const UnsignedBigInt &other ) const ; 107 bool o p e r a t o r!=( const UnsignedBigInt &other ) const ; 108 p r i v a t e : 109 std : : vector <int > b i t s ; 110 i n t s i g n ; 111 } ; UnsignedBigInt : : UnsignedBigInt ( void ) 117 { 118 b i t s. push_back ( 0 ) ; 119 s i g n = 1 ; 120 } UnsignedBigInt : : UnsignedBigInt ( const std : : s t r i n g s t r ) 123 { 124 s i g n = 1 ; 125 i n t l e n = s t r. s i z e ( ) ; 126 i f ( l e n == 0) b i t s. push_back ( 0 ) ; i n t t a i l = 0 ; 129 i f ( s t r [ t a i l ] == '-' ) 17

18 4 BIGINT 130 { 131 s i g n = 1; 132 t a i l ++; 133 } 134 f o r ( i n t i = l e n 1 ; i >= t a i l ; i ) 135 { 136 i f ( s t r [ i ] > '9' s t r [ i ] < '0' ) { b i t s. c l e a r ( ) ; return ; } 137 b i t s. push_back ( s t r [ i ] '0' ) ; 138 } } UnsignedBigInt UnsignedBigInt : : operator=( const std : : s t r i n g s t r ) 143 { 144 * t h i s = UnsignedBigInt ( s t r ) ; 145 return * t h i s ; 146 } UnsignedBigInt UnsignedBigInt : : operator=( const char * s t r ) 149 { 150 * t h i s = UnsignedBigInt ( s t r i n g ( s t r ) ) ; 151 return * t h i s ; 152 } UnsignedBigInt UnsignedBigInt : : operator=( i n t number ) 155 { 156 s t r i n g s t r = t o _ s t r i n g ( number ) ; * t h i s = UnsignedBigInt ( s t r ) ; 159 return * t h i s ; 160 } UnsignedBigInt UnsignedBigInt : : operator+( const UnsignedBigInt & other ) const 163 { 164 UnsignedBigInt r e s u l t ; 165 i f ( t h i s >s i g n * other. s i g n == 1) 166 {// 都是正数, 或者负数 167 r e s u l t = ADD(* t h i s, other ) ; 168 r e s u l t. s i g n = t h i s >s i g n ; 169 } 170 e l s e 171 { 172 i f (LESS(* t h i s, other ) ) 173 {// 第二个数大 174 r e s u l t = SUB( other, * t h i s ) ; 18

19 4 BIGINT 175 i f ( t h i s >s i g n == 1) 176 r e s u l t. s i g n = 1; 177 e l s e 178 r e s u l t. s i g n = 1 ; 179 } 180 e l s e 181 {// 第一个数大 182 r e s u l t = SUB(* t h i s, other ) ; 183 i f ( t h i s >s i g n == 1) 184 r e s u l t. s i g n = 1 ; 185 e l s e 186 r e s u l t. s i g n = 1; 187 } 188 } return r e s u l t ; 191 } UnsignedBigInt UnsignedBigInt : : operator+=(const UnsignedBigInt & other ) 194 { 195 UnsignedBigInt r e s u l t = * t h i s + other ; 196 * t h i s = r e s u l t ; 197 return r e s u l t ; 198 } UnsignedBigInt UnsignedBigInt : : operator ( const UnsignedBigInt & other ) const 201 { 202 UnsignedBigInt r e s u l t ; 203 i f ( t h i s >s i g n * other. s i g n == 1) 204 { 205 r e s u l t = ADD(* t h i s, other ) ; 206 r e s u l t. s i g n = t h i s >s i g n ; 207 } 208 e l s e 209 {// 都是正数, 或者负数 210 i f (LESS(* t h i s, other ) ) 211 {// 第二个数大 212 r e s u l t = SUB( other, * t h i s ) ; 213 i f ( t h i s >s i g n == 1) 214 r e s u l t. s i g n = 1; 215 e l s e 216 r e s u l t. s i g n = 1 ; 217 } 218 e l s e 219 {// 第一个数大 19

20 4 BIGINT 220 r e s u l t = SUB(* t h i s, other ) ; 221 i f ( t h i s >s i g n == 1) 222 r e s u l t. s i g n = 1 ; 223 e l s e 224 r e s u l t. s i g n = 1; 225 } 226 } return r e s u l t ; 229 } bool UnsignedBigInt : : operator <( const UnsignedBigInt & other ) const 232 { 233 i f ( b i t s. s i z e ( )!= other. b i t s. s i z e ( ) ) 234 return b i t s. s i z e ( ) < other. b i t s. s i z e ( ) ; f o r ( unsigned i n t i = b i t s. s i z e ( ) 1 ; i >= 0 ; i ) 237 { 238 i f ( b i t s [ i ]!= other. b i t s [ i ] ) 239 return b i t s [ i ] < other. b i t s [ i ] ; 240 } 241 return f a l s e ; 242 } bool UnsignedBigInt : : o p e r a t o r==(const UnsignedBigInt & other ) const 245 { 246 i f ( b i t s. s i z e ( )!= other. b i t s. s i z e ( ) ) 247 return f a l s e ; f o r ( unsigned i n t i = b i t s. s i z e ( ) 1 ; i >= 0 ; i ) 250 { 251 i f ( b i t s [ i ]!= other. b i t s [ i ] ) 252 return f a l s e ; 253 } 254 return true ; 255 } bool UnsignedBigInt : : o p e r a t o r!=( const UnsignedBigInt & other ) const 258 { 259 return! ( * t h i s==other ) ; 260 } bool UnsignedBigInt : : operator >( const UnsignedBigInt & other ) const 263 { 264 return other < * t h i s ; 20

21 4 BIGINT 265 } std : : istream& o p e r a t o r >> ( std : : istream &i s, UnsignedBigInt &b i g i n t ) 268 { 269 std : : s t r i n g b i g i n t _ s t r ; 270 i s >> b i g i n t _ s t r ; 271 b i g i n t = UnsignedBigInt ( b i g i n t _ s t r ) ; 272 return i s ; 273 } std : : ostream& operator <<(std : : ostream &os, const UnsignedBigInt &b i g i n t ) 276 { 277 i f ( b i g i n t. s i g n == 1) os << "-" ; 278 f o r ( i n t i = b i g i n t. b i t s. s i z e ( ) 1 ; i >= 0 ; i ) 279 os << b i g i n t. b i t s [ i ] ; 280 return os ; 281 } void Test ( ) 284 { 285 UnsignedBigInt a, b, c ; 286 a = UnsignedBigInt ( " " ) ; 287 b = UnsignedBigInt ( " " ) ; 288 c = UnsignedBigInt ( "999" ) ; 289 cout << "a = " << a << ", b = " << b << endl ; 290 cout << "a + b = " << a + b << endl ; 291 cout << "a - b = " << a b << endl ; 292 cout << "b - a = " << b a << endl ; 293 } i n t main ( ) 296 { 297 UnsignedBigInt a, b, c ; 298 a = " " ; 299 c = ; 300 cout << c << endl ; 301 while ( c i n >> b ) 302 { 303 cout << a + b << endl ; 304 cout << a b << endl ; 305 cout << ( a < b ) << endl ; 306 a += b ; 307 cout << a << endl ; 308 } 309 return 0 ; 21

22 4 BIGINT 310 } 22