1 #include<iostream>
2 #include<string>
3
4 using namespace std;
5
6 void BDplus(string str1, string str2)
7 {
8 int len1 = str1.length();
9 int len2 = str2.length();
10 char *value = NULL;
11 if (len1 >= len2)
12 {
13 //value= (char*)malloc(len1*sizeof(char));
14 value = new char[len1*sizeof(char)+1];
15 }
16 else if (len1 <= len2)
17 {
18 //value = (char*)malloc(len2*sizeof(char));
19 value = new char[len2*sizeof(char)+1];
20 }
21 int flag = 0;
22
23 int i = 0;
24 while (len1 > 0 && len2 > 0)
25 {
26 if (len1 <= 0 && len2 > 0)
27 {
28 len1 = 1;
29 str1[0] = '0';
30 }
31 else if (len1 > 0 && len2 <= 0)
32 {
33 len2 = 1;
34 str2[0] = '0';
35 }
36 int temp;
37 temp = (int)(str1[len1 - 1] - '0') + (int)(str2[len2 - 1] - '0');
38 value[i++] = (char)(temp % 10 + flag + (int)'0');
39 if (temp / 10 == 1)
40 {
41 flag = 1;
42 }
43 else
44 {
45 flag = 0;
46 }
47 len1--;
48 len2--;
49 }
50 if (flag == 1)
51 {
52 value[i++] = '1';
53 value[i] = '\0';
54 }
55 else
56 {
57 value[i] = '\0';
58 }
59 i--;
60 for(; i >= 0; i--)
61 {
62 cout << value[i];
63 }
64 }
65 void BDminus(string str1, string str2)
66 {
67 int len1, len2;
68 len1 = str1.length();
69 len2 = str2.length();
70 int flag = 0, i = 0;
71 int Case = 0;
72 char *value = NULL;
73
74 /*因为 string类重载了与string相比较的所有函数，包括<,>,==,>=,<=,!=*/
75
76 //if (len1 == len2)//两字符串长度相等
77 //{
78 // int j = 0;
79 // while ((j < len1) && (str1[j] == str2[j]))
80 // {
81 // j++;
82 // }
83 // if (j >= len1)//字符串1等于字符串2
84 // {
85 // Case = 1;
86 // }
87 // else //字符串1不等于字符串2
88 // {
89 // if (str1[j]>str2[j])//字符串1大于字符串2
90 // {
91 // Case = 1;
92 // }
93 // else //字符串1小于字符串2
94 // {
95 // Case = 2;
96 // }
97 // }
98
99 //}
100 //else if (len1 > len2)//字符串1长度大于字符串2
101 //{
102 // Case = 1;
103 //}
104 //else //字符串1长度小于字符串2
105 //{
106 // Case = 2;
107 //}
108
109 if(str1>=str2)// (Case==1)//情况一 大减小
110 {
111 value = (char *)malloc(len1*sizeof(char));
112 int temp;
113 while (len1 > 0 && len2 > 0)
114 {
115 if (flag == 1)//借位处理
116 {
117 if (str1[len1 - 1] == '0')
118 {
119 str1[len1 - 1] = '9';
120 flag = 1;
121 }
122 else if (str1[len1 - 1] != '0')
123 {
124 str1[len1 - 1] = str1[len1 - 1] - 1;
125 flag = 0;
126 }
127 }
128 if (str1[len1 - 1] >= str2[len2 - 1])
129 {
130 temp = (str1[len1 - 1] - '0') - (str2[len2 - 1] - '0');
131 flag = 0;
132 }
133 else
134 {
135 temp = (str1[len1 - 1] - '0') + 10 - (str2[len2 - 1] - '0');
136 flag = 1;
137 }
138 value[i++] = (char)(temp+(int)'0');
139 len1--;
140 len2--;
141 if (len1 > 0 && len2 <= 0)
142 {
143 len2 = 1;
144 str2[0] = '0';
145 }
146 }
147 }
148 else if (str1<str2)//(Case==2)//情况二 小减大
149 {
150 value = (char *)malloc(len2*sizeof(char));
151 int temp;
152 while (len1 > 0 && len2 > 0)
153 {
154 if (flag == 1)//借位处理
155 {
156 if (str2[len2 - 1] == '0')
157 {
158 str2[len2 - 1] = '9';
159 flag = 1;
160 }
161 else if (str2[len2 - 1] != '0')
162 {
163 str2[len2 - 1] = str2[len2 - 1] - 1;
164 flag = 0;
165 }
166 }
167 if (str2[len2 - 1] >= str1[len1 - 1])
168 {
169 temp = str2[len2 - 1] -str1[len1 - 1];
170 flag = 0;
171 }
172 else
173 {
174 temp = str2[len2 - 1] + 10 - str1[len1 - 1];
175 flag = 1;
176 }
177 value[i++] = (char)(temp + (int)'0');
178 len1--;
179 len2--;
180 if (len1 <= 0 && len2 > 0)
181 {
182 len1 = 1;
183 str1[0] = '0';
184 }
185 }
186 cout << "-";
187 }
188
189 value[i] = '\0';
190 i--;
191 while (i >= 0 && value[i] == '0')
192 {
193 i--;
194 }
195 if (i < 0)
196 {
197 cout << 0;
198 }
199 else
200 {
201 for(; i >= 0; i--)
202 {
203 cout << value[i];
204 }
205 }
206 }
207 int main(void)
208 {
209 string str1,str2,result;
210 cin >> str1>>str2;
211 BDplus(str1, str2);
212 BDminus(str1, str2);
213
214 return 0;
215 }
