大数相乘

#include <stdio.h>#include <string.h>#include <malloc.h>#define N 100int main(){int i,j;bool flag = false;char s1[N],s2[N];printf("输入被乘数:\n");scanf("%s",s1);printf("输入乘数:\n");scanf("%s",s2);int len1 = strlen(s1);int len2 = strlen(s2);int len = len1 + len2 + 1;char *a = (char*)malloc(len1*sizeof(char));char *b = (char*)malloc(len2*sizeof(char));char *c = (char*)malloc(len*sizeof(char));for(i=0;i<len;i++)c[i]=0;for(i=0;i<len1;i++)//倒置a[i] = s1[len1-1-i] - '0';for(i=0;i<len2;i++)b[i] = s2[len2-1-i] - '0';for(i=0;i<len1;i++)//各位相乘for(j=0;j<len2;j++)c[i+j] += a[i]*b[j];for(i=0;i<len;i++)//进位if(c[i] > 9){c[i+1] += c[i]/10;c[i] %= 10;}printf("结果为:\n");for(i=len-1;i>=0;i--){if(flag){c[i] += '0';printf("%c",c[i]);}else if(c[i] != 0)//判断最高位是不是0{c[i] += '0';printf("%c",c[i]);flag = true;}}printf("\n");free(a);free(b);free(c);a = NULL;b = NULL;c = NULL;return 0;}