#include<string.h>
#include <iostream>
#import <Foundation/Foundation.h>
using namespace std;
#define Int(X) (X - '0')
#define Char(X) (X + '0')
char a[100]={0};
char b[100]={0};
//求积
char *multiBigInteger( char *, char *);
//检查每个数的位数是否符合要求
BOOL checkNum( char *);
//把所求的积打印
void num(char*,int);
//求长度
int len(char*);
int main()
{
while (scanf("%s%s",a,b)) {
if(checkNum(a)||checkNum(b))
{
continue;
}else{
char * arr = multiBigInteger(a, b);
num(arr, len(arr));
}
// cout<<a<<endl<<b<<endl;
}
return 0;
}
BOOL checkNum( char *ch)
{
BOOL bo = NO;
char * temp = ch;
int lan = 0;
while (lan<strlen(temp)) {
//只要有一个不在0 到 9 的范围内返回 flase
if(temp[lan]<'0' || temp[lan]>'9'){
bo = YES;
cout<<"你输入的 "<<temp[lan]<<" 不符合要求,只能输入1到9任意一个!!!"<<endl;
break;
}
++temp;
++lan;
}
return bo;
}
void num(char* a,int len){
int temp = len;
cout<<"积是:";
// temp-=1;
for (;temp>=0;temp--) {
if (!((temp==len)&&(a[temp]=='0'))) {
cout<<a[temp];
}
// cout<<a[temp];
}
cout<<endl;
}
//求一个数组的长度
int len(char* a){
int len=0;
while (*a) {
++a;
++len;
}
return len;
}
char *multiBigInteger( char *a, char *b){
int lengtha = len(a);//a 的长度
int lengthb = len(b);//b 的长度
char* arrayab = nullptr;
//申请一块内存保存积
// arrayab=(char*)malloc((lengthb+lengtha-1)*sizeof(char));
arrayab= new char[lengthb+lengtha];
memset(arrayab, '0', (lengthb+lengtha)*sizeof(char));
cout<<arrayab[0]<<endl;
int ji = 0;
int jigewei = 0;
int jijinwei = 0;
int he = 0;
int hegeiwei = 0;
int hejinwei = 0;
int painyi = 0;
int temp = 0;
for (int i = lengthb-1; i>=0; i--) {//b
painyi = temp;
for (int j = lengtha-1; j>=0; j--) {//a
char chb = b[i];
char cha = a[j];
// cout<<cha<<chb<<endl;
// cout<< a[i]<<b[j]<<endl;
ji = Int(chb)*Int(cha)+jijinwei;
jigewei =ji%10;
jijinwei = ji/10;
// cout<<"lengtha"<<lengtha<<"lengthb"<<lengthb<<"ji"<<ji<<Int(cha)<<Int(chb)<<endl;
he = jigewei+hejinwei+Int(arrayab[painyi]);
hegeiwei= he%10;
hejinwei= he/10;
arrayab[painyi]=Char(hegeiwei);
arrayab[painyi+1]=Char(jijinwei);
++painyi;
}
++temp;
}
return arrayab;
}
参考博客地址: https://www.cnblogs.com/king-ding/p/bigIntegerMul.html请添加链接描述