Exponentiation

#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
char srcR[7], srcn[3];//string length, +1
int  dstR[5], dstn[2], point, n;//point记录小数点位置，n记录dstn的int形式；
int  ans[200], result[200];
int main()
{
    while (1)
    {
        if (scanf("%s", srcR) == EOF)
            break;
        getchar();
        scanf("%s", srcn);
        getchar();

        point = -1;
        int i, j;
        for (i = 0; i < 5; i++)
            dstR[i] = -1;
        for (i = 0; i < 2; i++)
            dstn[i] = -1;
        for (i = 0; i < 200; i++)
        {
            ans[i] = 0;
            result[i] = 0;
        }

        for (i = 0; srcR[i] != '.' && i < strlen(srcR); i++);
            if (srcR[i] == '.')
                point = i;

        j = 0;
        int Rtail;
        int hasPoint = 0;
        for (i = 0; i < strlen(srcR); i++)
            if (srcR[i] != '.')
                dstR[j++] = srcR[i] - '0';
            else
                hasPoint = 1;
        if (hasPoint && srcR[i-1] != '.')
            Rtail = i - 2;//记录R的结束,小数点占一位，循环多加了1,所以要减2
        else if (hasPoint && srcR[i-1] == '.')
            Rtail = i - 3;//结尾是小数点，要在多减1；
        else//无小数点
            Rtail = i - 1;
        j = 199;
        for (i = Rtail; i >= 0; i--)
            ans[j--] = dstR[i];
        for (i = 0; i < strlen(srcn); i++)
            dstn[i] = srcn[i] - '0';
        if (i == 2)
            n = dstn[0] * 10 + dstn[1];
        if (i == 1)
            n = dstn[0];

        int isZero = 1;
        for (i = 0; i < 6; i++)
            if (dstR[i] != 0 && dstR[i] != -1)
                isZero = 0;
        if (n == 0)
        {
            if (!isZero)
                printf("1\n");
            continue;
        }
        if (isZero)
        {
            if (n != 0)
                printf("0\n");
            continue;
        }
        //ans * dstR,dstR的每一位放在循环，ans放内循环
        int k;
        for (k = 0; k < n - 1; k++)
        {
            for (j = Rtail; j >= 0 ; j--)
            {
                for (i = 199; i >= 1; i--) // i>=1;
                {
                    result[i - (Rtail - j)] += ans[i] * dstR[j];
                    if (result[i - (Rtail - j)] >= 10)
                    {
                        result[i - (Rtail - j) - 1] += result[i - (Rtail - j)] / 10;
                        result[i - (Rtail - j)] = result[i - (Rtail - j)] % 10;
                    }
                }
            }
            for (i = 0; i < 200; i++)
            {
                 ans[i] = result[i];
                 result[i] = 0;//不要忘了清零；
            }
        }
        if (hasPoint)
        {
            point = (strlen(srcR) - point - 1) * n;
            point = 200 - point;
        }
        int start = 0, end = 0;
        //循环，直到遇到非零或小数点
        for (i = 0; i < 200; i++)
            if (ans[i] != 0)
                break;
        start = i;
        if (point < start && hasPoint)
            start = point - 1;
        if (hasPoint)
        {
            for (i = 199; i >= point; i--)
                if (ans[i] != 0)
                    break;
            end = i;
        }
        else
        {
            end = 199;
        }
        if (ans[start] == 0 && point == start + 1)
            start++;
        for (i = start ; i <= end; i++)
        {
            if (i == point && hasPoint)
                printf(".");
            printf("%d", ans[i]);
        }
        printf("\n");
    }
    return 0;
}