C#大数加减乘除取模

2019-04-13 16:52发布

站内文章 / 模拟电子
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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace 大数加减乘除 { class Program { static void Main(string[] args) { string a = "123456"; string b = "5"; int bigger = 0; char[] num1 = a.ToCharArray(); char[] num2 = b.ToCharArray(); bigger = num1BiggerThanNum2(num1, num2); string num1Addnum2 = Add(num1, num2); string num1Subnum2 = Sub(num1, num2); string num1Mutnum2 = Mut(num1, num2); string[] num1Desnum2 = Des(num1, num2); } /// /// 加法 /// /// /// /// 返回结果 public static string Add(char[] num1, char[] num2) { //对两个加数进行初始化，使长度相同 if (num1.Length > num2.Length) num2 = InitString(num1, num2); if (num1.Length < num2.Length) num1 = InitString(num1, num2); string result = ""; string finalRes = ""; //每一位相加都保留进位 int jinwei = 0; for (int i = num1.Length - 1; i >= 0; i--) { //将字符转换为数字 int res = num1[i] + num2[i] - 2 * '0' + jinwei; jinwei = 0; if (res >= 10) { jinwei = 1; res -= 10; } result += res; } if (jinwei > 0) result += jinwei; //将结果反转 for (int i = result.Length - 1; i >= 0; i--) { finalRes += result[i]; } //移除不必要的零 finalRes = RemoveZero(finalRes); return finalRes; } /// /// 减法 /// /// /// /// 返回结果 public static string Sub(char[] num1, char[] num2) { string result = ""; string finalRes = ""; //保留两个数相减的借位，用于下一位计算 int jiewei = 0; //判断两个数的大小，决定是否加“-”号 int bigger = num1BiggerThanNum2(num1, num2); if (bigger < 0) { char[] c = num1; num1 = num2; num2 = c; finalRes += '-'; } if (bigger == 0) return "0"; //将两个数初始化，使位数相同 if (num1.Length > num2.Length) num2 = InitString(num1, num2); if (num1.Length < num2.Length) num1 = InitString(num1, num2); for (int i = num1.Length - 1; i >= 0; i--) { //两数相减，不需要将字符转换为数字 int res = num1[i] - num2[i] - jiewei; jiewei = 0; if (res < 0) { res += 10; jiewei = 1; } result += res; } //将结果反转 for (int i = result.Length - 1; i >= 0; i--) { finalRes += result[i]; } finalRes = RemoveZero(finalRes); return finalRes; } /// /// 乘法 /// /// /// /// 返回结果 public static string Mut(char[] num1, char[] num2) { string finalRes = "0"; //判断大小，将较大的数放到上方，较小的数用来乘较大的数 int bigger = num1BiggerThanNum2(num1, num2); if (bigger < 0) { char[] c = num1; num1 = num2; num2 = c; } //两个数相乘的进位，用于计算 int jinwei = 0; for (int i = 0; i < num2.Length; i++) { string result = ""; string str = ""; for (int j = num1.Length - 1; j >= 0; j--) { int res = (num1[j] - '0') * (num2[num2.Length - i - 1] - '0') + jinwei; jinwei = 0; if (res >= 10) { int temp = res; res = res % 10; jinwei = temp / 10; } str += res; } if (jinwei > 0) str += jinwei; //将每一位相乘的结果反转 for (int k = str.Length - 1; k >= 0; k--) { result += str[k]; } //每相乘一位，都需要在末尾加零 for (int k = 0; k < i; k++) { result += "0"; } //将每一位相乘的结果与之前的结果相加 finalRes = Add(finalRes.ToCharArray(), result.ToCharArray()); } return finalRes; } /// /// 除法 /// /// /// /// 返回的字符数组中，第一个元素代表商，第二个元素代表余数 public static string[] Des(char[] num1, char[] num2) { string[] finalRes = new string[2]; //判断两个数的大小，如果除数大于被除数，则直接返回结果 int bigger = num1BiggerThanNum2(num1, num2); if (bigger < 0) { finalRes[0] = "0"; for (int i = 0; i < num1.Length; i++) { finalRes[1] += num1[i]; } } else if (bigger == 0) { finalRes[0] = "1"; finalRes[1] = "0"; } else//除数小于被除数 { //被除数，从除数的位数开始逐个记录 string beichushu = ""; string shang = ""; for (int i = 0; i < num2.Length; i++) { beichushu += num1[i]; } int flag = num2.Length - 1; for (int i = num2.Length - 1; i < num1.Length - 1; i++) { //第一轮除法计算完成，添加被除数下一位 if (num1BiggerThanNum2(beichushu.ToCharArray(), num2) < 0) { if (i + 1 == num1.Length) break; beichushu += num1[i + 1]; } //判断当前被除数是否大于除数，如果小于则添加被除数下一位 if (num1BiggerThanNum2(beichushu.ToCharArray(), num2) < 0) { if (i + 1 == num1.Length) break; beichushu += num1[i + 1]; shang += "0"; continue; } //判断当前除数与被除数大小，如果两数相等，则被除数减为0，商为1 if (num1BiggerThanNum2(beichushu.ToCharArray(), num2) == 0) { beichushu = "0"; shang += "1"; } //当除数小于被除数，则进行减法计算，看能够被多少个除数除 if (num1BiggerThanNum2(beichushu.ToCharArray(), num2) > 0) { string currentShang = "0"; for (int j = 1; num1BiggerThanNum2(beichushu.ToCharArray(), num2) >= 0; j++) { beichushu = Sub(beichushu.ToCharArray(), num2); currentShang = j.ToString(); } shang += currentShang; } } //将结果中多余的零去除 finalRes[0] = RemoveZero(shang); finalRes[1] = RemoveZero(beichushu); //如果商为0，则返回0 if (finalRes[1] == "") finalRes[1] = "0"; } return finalRes; } /// /// 将两个字符串进行初始化，以达到相同的长度，在较短的字符串前边补零 /// /// /// /// 返回初始化后的字符串 public static char[] InitString(char[] a, char[] b) { int aLength = a.Length; int bLength = b.Length; char[] c = new char[Math.Max(aLength, bLength)]; int start = Math.Abs(aLength - bLength); for (int i = 0; i < Math.Max(aLength, bLength); i++) { if (i < start) c[i] = '0'; else { if (aLength > bLength) c[i] = b[i - start]; if (aLength < bLength) c[i] = a[i - start]; } } return c; } /// /// 判断两个数的大小 /// /// /// /// num1大于num2，则返回1；num1等于num2，则返回0；num1小于num2，则返回-1； public static int num1BiggerThanNum2(char[] num1, char[] num2) { if (num1.Length > num2.Length) { return 1; } if (num1.Length < num2.Length) { return -1; } if (num1.Length == num2.Length) { for (int i = 0; i < num2.Length; i++) { if (num1[i] > num2[i]) return 1; else if (num1[i] < num2[i]) return -1; } } return 0; } /// /// 移除字符串前边不必要的零 /// /// /// 返回正确字符串 public static string RemoveZero(string str) { string result = ""; bool start = false; for (int i = 0; i < str.Length; i++) { if (str[i] != '0') { start = true; } if (start) result += str[i]; } return result; } } }

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