longDataMinus.c

#include <stdio.h>
#include <string.h>
#include <malloc.h>
#define MAX_DATA_LEN 1000

int findIntNum(char* str)//整数个数
{
    int i=0,dotPos=0;
    for(i=0;i<=strlen(str)-1;++i)
    {
        if((str[i])==‘.‘)
        {
            return i;
        }
    }
    return i;
}

int findDotNum(char* str)
{
    //找到小数点,从右往左第几位,0开始.小数个数
    if(strlen(str)==findIntNum(str))
		return 0;
	else
	    return strlen(str)-findIntNum(str)-1;
}

//第一个为minuend,第二个为subtractor
int valueCompare(char *sub1,char* sub2)
{
    int len_str1,len_str2;
    int IntNum1=0,IntNum2=0;
    len_str1=strlen(sub1);
    len_str2=strlen(sub2);
    IntNum1=findIntNum(sub1);
    IntNum2=findIntNum(sub2);
//printf("len_str1=%d,len_str2=%d,IntNum1=%d,IntNum2=%d\n",len_str1,len_str2,IntNum1,IntNum2);
    if(IntNum1 < IntNum2)
       return 1;
    else if((IntNum1==IntNum2) && (sub1[0]<sub2[0]))
       return 1;
    return 0;
}

char* minus(char* sub1,char* sub2)
{
    int t,i,len_str1,len_str2,resultLenMax;
    int borrow=0;
	int IntNum1=0,IntNum2=0,dotPos1=0,dotPos2=0,shift=0;
    int a[1001]={0},b[1001]={0},c[1001]={0};
    char* sub;

    len_str1=strlen(sub1);
    for(i=0;i<=len_str1-1;++i)
        a[i]=sub1[len_str1-1-i]-‘0‘;

    len_str2=strlen(sub2);
    for(i=0;i<=len_str2-1;++i)
        b[i]=sub2[len_str2-1-i]-‘0‘;

    IntNum1=findIntNum(sub1);
    IntNum2=findIntNum(sub2);
    dotPos1=findDotNum(sub1);
    dotPos2=findDotNum(sub2);

	resultLenMax=(IntNum1>IntNum2?IntNum1:IntNum2) + (dotPos1>dotPos2?dotPos1:dotPos2) + 1;

	sub=(char *)malloc(resultLenMax * sizeof(char));
	if(NULL==sub)
    {
		printf("malloc ERROR!\n");
       	return;
    }
	memset(sub,0,resultLenMax);

    if((dotPos1==0) && (dotPos2==0))//没有小数
    {
        for(i=0;i<=resultLenMax-1;i++)
        {
            c[i]=((a[i]-b[i]-borrow)>=0) ? (a[i]-b[i]-borrow):(a[i]-b[i]-borrow+10);
            borrow=((a[i]-b[i]-borrow)>=0) ? 0 : 1;
        }
    }

    else if(dotPos1==0)//被减数没小数,减数有小数
    {
        shift=dotPos2;
        for(i=0;i<=dotPos2-1;i++)
        {
            c[i]=((0-b[i]-borrow)>=0) ? (0-b[i]-borrow):(0-b[i]-borrow+10);
            borrow=((0-b[i]-borrow)>=0) ? 0 : 1;
			//printf("\nc[%d]=%c\n",i,c[i]+‘0‘);
        }
        c[dotPos2]=‘.‘-‘0‘;
        for(i=dotPos2+1;i<=resultLenMax-1;i++)
        {
            c[i]=((a[i-shift-1]-b[i]-borrow)>=0) ? (a[i-shift-1]-b[i]-borrow):(a[i-shift-1]-b[i]-borrow+10);
            borrow=((a[i-shift-1]-b[i]-borrow)>=0) ? 0 : 1;
        }
    }

    else if(dotPos2==0)//被减数有小数,减数没有小数
    {
        shift=dotPos1;
        for(i=0;i<=dotPos1-1;i++)
        {
            c[i]=a[i];
        }
        c[dotPos1]=‘.‘-‘0‘;
        for(i=dotPos1+1;i<=resultLenMax-1;i++)
        {
            c[i]=((a[i]-b[i-shift-1]-borrow)>=0) ? (a[i]-b[i-shift-1]-borrow):(a[i]-b[i-shift-1]-borrow+10);
            borrow=((a[i]-b[i-shift-1]-borrow)>=0) ? 0 : 1;
        }
    }

    else if(dotPos1-dotPos2==0)//2个数都有小数，且小数位数相等
    {
        for(i=0;i<=dotPos1-1;i++)
        {
            c[i]=((a[i]-b[i]-borrow)>=0) ? (a[i]-b[i]-borrow):(a[i]-b[i]-borrow+10);
            borrow=((a[i]-b[i]-borrow)>=0) ? 0 : 1;
        }
        c[dotPos1]=‘.‘-‘0‘;
        for(i=dotPos1+1;i<=resultLenMax-1;i++)
        {
            c[i]=((a[i]-b[i]-borrow)>=0) ? (a[i]-b[i]-borrow):(a[i]-b[i]-borrow+10);
            borrow=((a[i]-b[i]-borrow)>=0) ? 0 : 1;
        }
    }

    else if(dotPos1-dotPos2<0)//2个数都有小数，减数位数多
    {
        shift=dotPos2-dotPos1;
        for(i=0;i<=shift-1;i++)
        {
            c[i]=((0-b[i]-borrow)>=0) ? (0-b[i]-borrow):(0-b[i]-borrow+10);
            borrow=((0-b[i]-borrow)>=0) ? 0 : 1;
        }
        for(i=shift;i<=dotPos2-1;i++)
        {
            c[i]=((a[i-shift]-b[i]-borrow)>=0) ? (a[i-shift]-b[i]-borrow):(a[i-shift]-b[i]-borrow+10);
            borrow=((a[i-shift]-b[i]-borrow)>=0) ? 0 : 1;
        }
        c[dotPos2]=‘.‘-‘0‘;
        for(i=dotPos2+1;i<=resultLenMax-1+shift;i++)
        {
            c[i]=((a[i-shift]-b[i]-borrow)>=0) ? (a[i-shift]-b[i]-borrow):(a[i-shift]-b[i]-borrow+10);
            borrow=((a[i-shift]-b[i]-borrow)>=0) ? 0 : 1;
        }
    }

    else if(dotPos1-dotPos2>0)
    {
        shift=dotPos1-dotPos2;
        for(i=0;i<=shift-1;i++)
        {
            c[i]=((a[borrow]-0-borrow)>=0) ? (a[borrow]-0-borrow):(a[borrow]-0-borrow+10);
            borrow=((a[borrow]-0-borrow)>=0) ? 0 : 1;
        }
        for(i=shift;i<=dotPos1-1;i++)
        {
            c[i]=((a[i]-b[i-shift]-borrow)>=0) ? (a[i]-b[i-shift]-borrow):(a[i]-b[i-shift]-borrow+10);
            borrow=((a[i]-b[i-shift]-borrow)>=0) ? 0 : 1;
        }
        c[dotPos1]=‘.‘-‘0‘;
        for(i=dotPos1+1;i<=resultLenMax-1+shift;i++)
        {
            c[i]=((a[i]-b[i-shift]-borrow)>=0) ? (a[i]-b[i-shift]-borrow):(a[i]-b[i-shift]-borrow+10);
            borrow=((a[i]-b[i-shift]-borrow)>=0) ? 0 : 1;
        }
    }
    for(i=resultLenMax-1+shift;i>=0;i--)
            sub[resultLenMax-1+shift-i]=c[i]+‘0‘;

//最高位借完为0没处理
//	while(i++)
	//    if(sub[i]==0)sub[i]==‘\0‘;
	//printf("%s\n",sub);
    return sub;
}

int main()
{
    int key=0;
    char str1[MAX_DATA_LEN],str2[MAX_DATA_LEN];
	char* result;
    printf("Please input two big data:\n");

	result=(char *)malloc(2 * MAX_DATA_LEN * sizeof(char));
	if(NULL==result)
    {
		printf("malloc ERROR!\n");
       	return;
    }
	memset(result,0,2 * MAX_DATA_LEN);

    scanf("%s",str1);//输入有效性判断
    scanf("%s",str2);

    key=valueCompare(str1,str2);
    printf("The minus result of the two big data is:");
    if(key==1)
    {
        printf("-");
		result=minus(str2,str1);
    }
    else
    {
        result=minus(str1,str2);
    }
    printf("%s\n",result);

free(result);

    return 0;
}