高精度c++

1.步骤

1.字符串输入

2.倒序存储给数字数组

3.进行加减法要进位或借位

4.倒序输出

2.高精度加法

#include <iostream>
using namespace std;
int main(){
	string c1,c2;
	cin >> c1 >> c2;
	int a[1000] = {},b[1000] = {},c[1000] = {},jin = 0;
	int len1 = c1.length(),len2 = c2.length();
	for (int i = 0; i < len1; i++){
		a[len1-1-i] = c1[i]-'0';
	}
	for (int i = 0; i < len2; i++){
		b[len2-1-i] = c2[i]-'0';
	}
	int len = max(len1,len2);
	for (int i =0; i < len; i++){
		c[i] = a[i] + b[i] +jin;
		jin = c[i]/10;
		c[i] = c[i] % 10;
	}
	if (jin !=0) {
		c[len++] = jin;
	}
	for (int i = 0; i < len; i++){
		cout << c[len-1-i];
	}
	return 0;
}

3.高精度减法

#include <iostream>
using namespace std;
int main(){
	string c1,c2;
	cin >> c1 >> c2;
	int a[1000] = {},b[1000] = {},c[1000] = {},jin = 0;
	int len1 = c1.length(),len2 = c2.length();
	if (len1 < len2 || c1 < c2 && len1 == len2){
	    swap(c1,c2);
	    swap(len1,len2);
	    cout << "-";
	}
	for (int i = 0; i < len1; i++){
		a[len1-1-i] = c1[i]-'0';
	}
	for (int i = 0; i < len1; i++){
		b[len2-1-i] = c2[i]-'0';
	}
	for (int i =0; i < len1; i++){
	    if (a[i] < b[i]){
	        a[i] += 10;
	        a[i+1] --;
	    }
		c[i] = a[i] - b[i];
		
	}
	while (c[len1-1] ==0 and len1 > 1){
	    len1 --;
	}
	for (int i = 0; i < len1; i++){
		cout << c[len1-1-i];
	}
	return 0;
}

4.高精度乘法

中间计算过程是先乘再进位。

#include <bits/stdc++.h>
using namespace std;
int main(){
	char c1[205], c2[205];
	int a[205] = {}, b[205] = {}, c[405] = {};
	scanf("%s %s", c1, c2);
	int len1 = strlen(c1), len2 = strlen(c2);
	for (int i = 0; i < len1; i++){	
	    a[len1 - 1 - i] = c1[i] - '0';
	}
	for (int i = 0; i < len2; i++){
	    b[len2 - 1 - i] = c2[i] - '0';
	}	
	for (int i = 0; i < len1; i++) {
		for (int j = 0; j < len2; j++) {
			c[i + j] += a[i] * b[j];
		}
	}
	int len = len1 + len2;
	for (int i = 0; i < len; i++) {
		c[i + 1] += c[i] / 10;
		c[i] = c[i] % 10;
	}
	while (c[len - 1] == 0 && len > 1) { 
		len--;
	}
	for (int i = len - 1; i >= 0; i--) 	printf("%d", c[i]);	
	return 0;
}