加法：
1 char * add(char *s, char *ss) { 2 memset(str3, 0, sizeof(str3)); 3 int len1 = strlen(s)-1; 4 int len2 = strlen(ss)-1; 5 int len3 = 0, x, y, flag = 0; 6 while(len1 >= 0 || len2 >= 0) { 7 if(len1 >= 0) x = s[len1] - '0'; 8 else x = 0; 9 if(len2 >= 0) y = ss[len2] - '0'; 10 else y = 0; 11 str3[len3++] = (x+y+flag)%10 + '0'; 12 flag = (x+y+flag)/10; 13 len2--;len1--; 14 } 15 if(flag) str3[len3++] = '1'; 16 for(int i = 0; i < len3/2; i ++) { 17 swap(str3[i],str3[len3-i-1]); 18 } 19 return str3; 20 }
减法：
1 char *sub(char *s, char *ss) { 2 memset(str3, 0, sizeof(str3)); 3 int len1 = strlen(s)-1, len2 = strlen(ss)-1; 4 int flag = 1, len3 = 0, x, y, cnt = 0; 5 if(strcmp(s,ss) == 0){ 6 str3[len3++] = '0'; 7 return str3; 8 } 9 if(len1 < len2 || (len1==len2&&strcmp(s,ss)<0)) { 10 swap(len1,len2); 11 swap(s,ss); 12 flag = 0; 13 } 14 while(len1 >= 0 || len2 >= 0) { 15 if(len1 >= 0) x = s[len1--] - '0'; 16 else x = 0; 17 if(len2 >= 0) y = ss[len2--] - '0'; 18 else y = 0; 19 int ans = x-y+cnt; 20 if(ans < 0) { 21 str3[len3++] = ans+10+'0'; 22 cnt = -1; 23 } else { 24 str3[len3++] = ans+'0'; 25 cnt = 0; 26 } 27 } 28 while(str3[len3-1] == '0') { 29 str3[--len3] = ' '; 30 } 31 if(!flag) str3[len3++] = '-'; 32 for(int i = 0; i < len3/2; i ++) swap(str3[i], str3[len3-i-1]); 33 return str3; 34 }
乘法：
1 int mul(char *s, char *ss,int *num) { 2 int len1 = strlen(s); 3 int len2 = strlen(ss); 4 int len3 = len1+len2; 5 for(int i = 0; i < len1/2; i ++) swap(s[i],s[len1-i-1]); 6 for(int i = 0; i < len2/2; i ++) swap(ss[i],ss[len2-i-1]); 7 for(int i = 0; i < len1; i ++) { 8 for(int j = 0; j < len2; j ++) { 9 num[i+j] += (s[i]-'0')*(ss[j]-'0'); 10 } 11 } 12 for(int i = 0; i < len3; i ++) { 13 if(num[i] >= 10) { 14 num[i+1] += num[i]/10; 15 num[i] %= 10; 16 } 17 } 18 while(num[len3] == 0 && len3 >= 0) len3--; 19 len3++; 20 for(int i = 0; i < len3/2; i ++) { 21 swap(num[i], num[len3-i-1]); 22 } 23 if(!len3) len3++; 24 return len3; 25 }
1 std::string StringMul(const std::string& left, const std::string& right) { 2 bool flag1 = (left[0] == '-'), flag2 = (right[0] == '-'); 3 string s1, s2, result; 4 if(flag1) s1 = left.substr(1,left.length()); 5 else s1 = left; 6 if(flag2) s2 = right.substr(1,right.length()); 7 else s2 = right; 8 int len1 = s1.length(); 9 int len2 = s2.length(); 10 int len3 = len1+len2; 11 vector<int> num(len3+2, 0); 12 for(int i = 0; i < len1/2; i ++) swap(s1[i],s1[len1-i-1]); 13 for(int i = 0; i < len2/2; i ++) swap(s2[i],s2[len2-i-1]); 14 for(int i = 0; i < len1; i ++) { 15 for(int j = 0; j < len2; j ++) { 16 num[i+j] += (s1[i]-'0')*(s2[j]-'0'); 17 } 18 } 19 for(int i = 0; i < len3; i ++) { 20 if(num[i] >= 10) { 21 num[i+1] += num[i]/10; 22 num[i] %= 10; 23 } 24 } 25 26 while(num[len3] == 0 && len3 >= 0) len3--; 27 len3++; 28 for(int i = 0; i < len3/2; i ++) { 29 swap(num[i], num[len3-i-1]); 30 } 31 for(int i = 0; i < len3; i ++) { 32 result = result + char(num[i]+'0'); 33 } 34 if(!len3) return "0"; 35 if((flag1&&!flag2) || (!flag1&&flag2)) result = '-' + result; 36 return result; 37 }
Java的加减乘法：
1 import java.util.Scanner; 2 import java.math.BigDecimal; 3 import java.math.BigInteger; 4 5 public class Main{ 6 public static void main(String[] args) { 7 Scanner cin = new Scanner(System.in); 8 BigDecimal a = cin.nextBigDecimal(); 9 BigDecimal b = cin.nextBigDecimal(); 10 BigInteger aa = cin.nextBigInteger(); 11 BigInteger bb = cin.nextBigInteger(); 12 System.out.println("a+b:"+a.add(b)); 13 System.out.println("a-b:"+a.subtract(b)); 14 System.out.println("a*b:"+a.multiply(b)); 15 System.out.println("a/b:"+aa.divide(bb)); 16 System.out.println("a^10:"+a.pow(10)); 17 } 18 }