Bign
1 #include<iostream> 2 #include<string> 3 #include<cstring> 4 #include<cstdio> 5 using namespace std; 6 const int maxn = 1000 + 5; 7 8 class bign 9 { 10 public: 11 int len, s[maxn]; 12 bign() 13 { 14 len = 0; 15 memset(s, 0, sizeof(s)); 16 } 17 bign operator = (const char *num) 18 { 19 //支持对字符数组的赋值 20 len = strlen(num); 21 for(int i = 0; i < len; ++i) 22 s[i] = num[len-i-1] - '0'; 23 return *this; 24 } 25 bign(const char *num) 26 { 27 //初始化 28 *this = num; 29 } 30 bign operator = (int num) 31 { 32 //支持对整型数的赋值 33 char s[maxn]; 34 sprintf(s, "%d", num); 35 *this = s; 36 return *this; 37 } 38 bign(int num) 39 { 40 //初始化 41 *this = num; 42 } 43 string str() const 44 { 45 //x.str()不会改变x 46 string str = ""; 47 for(int i = 0; i < len; ++i) 48 str += (char)(s[i] + '0');//str = str + s[i] +'0'也可以 49 if(str == "") 50 str = "0"; 51 return str; 52 } 53 friend istream& operator>>(istream &in, bign& b);/* 54 { 55 string str; 56 in >> str; 57 b = str.c_str(); 58 return in; 59 }*/ 60 friend ostream& operator<<(ostream &out, bign& b);/* 61 { 62 out << b.str(); 63 return out; 64 }*/ 65 bign operator +(const bign& b) const 66 { 67 bign c; 68 c.len = 0; 69 /* 70 int d = 0, i = 0; 71 for(; d || i < max(len, b.len); ++i) 72 { 73 int x = d; 74 if(i < len) 75 x += s[i]; 76 if(i < b.len) 77 x += b.s[i]; 78 c.s[c.len++] = x % 10; 79 g = x % 10; 80 } 81 */ 82 // memset(c, 0, sizeof(c)); 83 int i = 0, d = 0; 84 for(; i < max(len, b.len)+1; ++i) 85 { 86 int x = s[i] + b.s[i] + d; 87 d = c.s[i] / 10; 88 x %= 10; 89 c.s[c.len++] = x; 90 } 91 if(d == 0) 92 --c.len; 93 return c; 94 } 95 bign operator +=(const bign& b) 96 { 97 *this = *this + b; 98 return *this; 99 } 100 bool operator <(const bign& b) const 101 { 102 if(len != b.len) 103 return len < b.len; 104 for(int i = len-1; i >= 0; --i) 105 if(s[i] != b.s[i]) 106 return s[i] < b.s[i]; 107 return false; 108 } 109 bool operator >(const bign& b) const 110 { 111 return b < *this; 112 } 113 bool operator <= (const bign& b) const 114 { 115 return !(*this > b); 116 } 117 bool operator >=(const bign& b) const 118 { 119 return !(*this < b); 120 } 121 bool operator ==(const bign& b) const 122 { 123 return !(*this < b) && (*this > b); 124 } 125 }; 126 127 inline istream& operator>>(istream &in, bign& b) 128 { 129 string str; 130 in >> str; 131 b = str.c_str(); 132 return in; 133 } 134 inline ostream& operator<<(ostream &out, bign& b) 135 { 136 out << b.str(); 137 return out; 138 } 139 int main() 140 { 141 return 0; 142 }
下面是一些实验：
Test
1 #include<iostream> 2 #include<sstream> 3 #include<cstring> 4 #include<cstdio> 5 using namespace std; 6 7 int main() 8 { 9 __int64 n; 10 char a[1000]; 11 while(cin >> n) 12 { 13 //注意整数不能溢出，cin返回错误直接退出 14 stringstream ss; 15 ss << n; 16 string str; 17 ss >> str; 18 cout << str; 19 cout << endl; 20 /* 21 //还是用C++的stringstream好，C的__int64依然是当做普通int操作的，容易出错 22 sprintf(a, "%d", n); 23 for(int i = 0; i < strlen(a); ++i) 24 cout << a[i]; 25 */ 26 cout << endl << "**********************String****************************" << endl; 27 string str = ""; 28 //对string串字符方式的赋值 29 for(int i = 0; i < strlen(a); ++i) 30 str += (char)(a[i]); 31 if(str == "") 32 str = "0"; 33 cout << str; 34 cout << endl << "**********************Input****************************" << endl; 35 } 36 return 0; 37 }