大整数加法

#include <stdio.h>#include <string.h>#include <stdlib.h>void add(char *a,char *b,char *s){int a_len=strlen(a);int b_len=strlen(b);int i,temp,k;char *a0=(char *)malloc(sizeof(char)*b_len);char *b0=(char *)malloc(sizeof(char)*a_len);int*a1=(int *)malloc(sizeof(int)*b_len);int *b1=(int *)malloc(sizeof(int)*b_len);int*s1=(int *)malloc(sizeof(int)*(b_len+1));int*a2=(int *)malloc(sizeof(int)*a_len);int *b2=(int *)malloc(sizeof(int)*a_len);int*s2=(int *)malloc(sizeof(int)*(a_len+1));if (a_len>=b_len){k=b_len;for (i=0;i<a_len;i++)s2[i]=0;for (i=0;i<a_len;i++)b0[i]='0';for (i=a_len-1;i>=a_len-b_len;i--)b0[i]=b[--k];for (i=0;i<a_len;i++){a2[i]=a[i]-'0';}for (i=0;i<a_len;i++)b2[i]=b0[i]-'0';for (i=a_len-1;i>=0;i--){temp=a2[i]+b2[i]+s2[i];if (temp>=10){s2[i]=temp%10;s2[i-1]=1;}else{s2[i]=temp;}}for (i=0;i<=a_len;i++){s[i]=s2[i]+'0';}//itoa(s2,s,10);}else {k=a_len;for (i=0;i<b_len;i++)a0[i]='0';for (i=0;i<b_len;i++)s1[i]=0;for (i=b_len-1;i>=b_len-a_len;i--)a0[i]=a[--k];for (i=0;i<b_len;i++){a1[i]=a0[i]-'0';b1[i]=b[i]-'0';}for (i=b_len-1;i>=0;i--){temp=a1[i]+b1[i]+s1[i];if (temp>=10){s1[i]=temp%10;s1[i-1]=1;}else{s1[i]=temp;}}for (i=0;i<b_len;i++){s[i]=s1[i]+'0';}}}void main(){char a[20]={0};char b[20]={0};char s[20]={0};int n;printf("Input two big number:\n");scanf("%s %s",a,b);n=atoi(a);printf("%d\n",n);add(a,b,s);printf("Output number:\n");printf("%s",s);printf("\n");system("pause");}