大数四则运算java
1 // 大数的四则运算 2 #include <iostream> 3 #include <string> 4 #include <algorithm> 5 using namespace std; 6 7 class BIGINTEGEROPERATIONS 8 { 9 private: 10 static int COMPARE(string number1, string number2) 11 { 12 int j; 13 14 int length1 = number1.size(); 15 int length2 = number2.size(); 16 17 if(number1.size() == 0) number1 = "0"; 18 if(number2.size() == 0) number2 = "0"; 19 20 j = 0; 21 for(int i = 0; i < length1; ++i) 22 { 23 if(number1[i] == ‘0‘) ++j; 24 else break; 25 } 26 number1 = number1.substr(j); 27 28 j = 0; 29 for(int i = 0; i < length2; ++i) 30 { 31 if(number2[i] == ‘0‘) ++j; 32 else break; 33 } 34 number2 = number2.substr(j); 35 36 length1 = number1.size(); 37 length2 = number2.size(); 38 39 if(length1 > length2) 40 { 41 return 1; 42 } 43 else if(length1 == length2) 44 { 45 if(number1.compare(number2) > 0) 46 { 47 return 1; 48 } 49 else if(number1.compare(number2) == 0) 50 { 51 return 0; 52 } 53 else 54 { 55 return -1; 56 } 57 } 58 else 59 { 60 return -1; 61 } 62 63 return 0; 64 } 65 66 public: 67 static string PLUS(string number1,string number2) 68 { 69 int i; 70 int length1 = number1.size(); 71 int length2 = number2.size(); 72 73 string result=""; 74 75 reverse(number1.begin(), number1.end()); 76 reverse(number2.begin(), number2.end()); 77 78 for(i = 0; i < length1 && i < length2; i++) 79 { 80 char c = (char)(number1[i] + number2[i] - 48); 81 result = result + c; 82 } 83 84 while(i < length1) 85 { 86 result = result + number1[i]; 87 ++i; 88 } 89 90 while(i < length2) 91 { 92 result = result + number2[i]; 93 ++i; 94 } 95 96 int carry = 0; 97 for(i = 0; i < (int)result.size(); ++i) 98 { 99 int value = result[i] - 48 + carry; 100 result[i] = (char)(value % 10 + 48); 101 carry = value / 10; 102 } 103 104 if(carry !=0 ) 105 { 106 result = result + (char)(carry + 48); 107 } 108 109 for(i = result.size() - 1; i >= 0; i--) 110 { 111 if(result[i] != ‘0‘) break; 112 } 113 114 result = result.substr(0, i + 1); 115 116 reverse(result.begin(), result.end()); 117 if(result.length() == 0) result = "0"; 118 return result; 119 } 120 121 122 static string MINUS(string number1,string number2) 123 { 124 int i; 125 string result = ""; 126 127 int length1 = number1.size(); 128 int length2 = number2.size(); 129 130 if(COMPARE(number2,number1) > 0) 131 { 132 return "-" + MINUS(number2, number1); 133 } 134 135 reverse(number1.begin(),number1.end()); 136 reverse(number2.begin(),number2.end()); 137 138 for(i = 0; i < length1 && i < length2; i++) 139 { 140 char c = number1[i] - number2[i] + 48; 141 result = result + c; 142 } 143 144 if(i < length1) 145 { 146 for(; i < length1; i++) 147 { 148 result = result + number1[i]; 149 } 150 } 151 152 int carry = 0; 153 for(i = 0; i < (int)result.length(); i++) 154 { 155 int value = result[i] - 48 + carry; 156 if(value < 0) 157 { 158 value = value + 10; 159 carry = -1; 160 } 161 else carry = 0; 162 result[i]=(char)(value + 48); 163 } 164 165 for(i = result.size() - 1; i >= 0; i--) 166 { 167 if(result[i] != ‘0‘)break; 168 } 169 170 result = result.substr(0, i+1); 171 172 reverse(result.begin(), result.end()); 173 if(result.length()==0) result = "0"; 174 return result; 175 } 176 177 178 static string MULTIPLY(string number1, string number2) 179 { 180 int i, j; 181 int *iresult; 182 int length1 = number1.size(); 183 int length2 = number2.size(); 184 string result = ""; 185 186 reverse(number1.begin(), number1.end()); 187 reverse(number2.begin(), number2.end()); 188 189 iresult = (int*)malloc(sizeof(int) * (length1 + length2 + 1)); 190 memset(iresult, 0, sizeof(int) * (length1 + length2 + 1)); 191 192 for(i = 0; i < length1; i++) 193 { 194 for(j = 0; j < length2; j++) 195 { 196 iresult[i+j] += ((number1[i] - 48) * (number2[j] - 48)); 197 } 198 } 199 200 int carry = 0; 201 for(i = 0; i < length1 + length2; i++) 202 { 203 int value = iresult[i] + carry; 204 iresult[i] = value % 10; 205 carry = value / 10; 206 } 207 208 for(i = length1 + length2 - 1; i >= 0; i--) 209 { 210 if(iresult[i] != 0)break; 211 } 212 213 for(; i >= 0; i--) 214 { 215 result = result + (char)(iresult[i]+48); 216 } 217 218 free(iresult); 219 220 if(result == "") result = "0"; 221 return result; 222 } 223 224 225 // 缺省地,商数向下取整, floatpoint用于指定保留小数点的位数 226 static string DIVIDE(string number1, string number2, int floatpoint = 0) 227 { 228 int i, j, pos; 229 string result = ""; 230 string tempstr = ""; 231 int length1 = number1.size(); 232 int length2 = number2.size(); 233 234 if((COMPARE(number2, number1) > 0) && (floatpoint == 0)) 235 { 236 return "0"; 237 } 238 239 tempstr = number1.substr(0, length2); 240 pos = length2 - 1; 241 242 while(pos < length1) 243 { 244 int quotient = 0; 245 while(COMPARE(tempstr, number2) >= 0) 246 { 247 quotient++; 248 tempstr = MINUS(tempstr, number2); 249 } 250 251 result = result + (char)(quotient + 48); 252 pos++; 253 if(pos < length1) 254 { 255 tempstr += number1[pos]; 256 } 257 } 258 259 if(floatpoint > 0) 260 { 261 result += ‘.‘; 262 string stmp = "1"; 263 int itmp = 0; 264 for(int k = 0; k < floatpoint; ++k) 265 { 266 stmp += ‘0‘; 267 if(COMPARE(MULTIPLY(MINUS(number1, MULTIPLY(DIVIDE(number1, number2), number2)), stmp), number2) < 0) 268 { 269 result += ‘0‘; 270 ++itmp; 271 } 272 } 273 274 string temp = DIVIDE(MULTIPLY(MINUS(number1, MULTIPLY(DIVIDE(number1, number2), number2)), stmp), number2); 275 if(temp[0] != ‘0‘) result += temp; 276 } 277 278 j = result.size(); 279 for(i = 0; i < j; i++) 280 { 281 if(result[i] != ‘0‘) break; 282 } 283 284 result = result.substr(i, j); 285 286 return result; 287 } 288 289 static string MOD(string number1, string number2) 290 { 291 if(COMPARE(number2, number1) > 0) 292 { 293 return number1; 294 } 295 else if(COMPARE(number2, number1) == 0) 296 { 297 return "0"; 298 } 299 else 300 { 301 return MINUS(number1, MULTIPLY(DIVIDE(number1, number2), number2)); 302 } 303 } 304 }; 305 306 int main(int argc, char* argv[]) 307 { 308 string str1 = "9999999999999999999999999999999999999999"; 309 string str2 = "9998999899989998999899989998999899989998"; 310 311 cout << BIGINTEGEROPERATIONS::PLUS(str1, str2) << endl; 312 cout << "===============" << endl; 313 cout << BIGINTEGEROPERATIONS::MINUS(str1, str2) << endl; 314 cout << "===============" << endl; 315 cout << BIGINTEGEROPERATIONS::MULTIPLY(str1, str2) << endl; 316 cout << "===============" << endl; 317 cout << BIGINTEGEROPERATIONS::DIVIDE(str1, str2, 4) << endl; 318 cout << "===============" << endl; 319 cout << BIGINTEGEROPERATIONS::MOD(str1, str2) << endl; 320 321 return 0; 322 }
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