大数的四则运算模板(高精度加减乘除)

普通大数运算

对于不同的题目要求,在main函数里修改就可以了

const int MAXSIZE = 200;

void Add(char *str1, char *str2, char *str3);
void Minus(char *str1, char *str2, char *str3);
void Mul(char *str1, char *str2, char *str3);
void Div(char *str1, char *str2, char *str3);

int main()
{
    char str1[MAXSIZE], str2[MAXSIZE], str3[MAXSIZE];
    while (scanf("%s %s", str1, str2) == 2)
    {
        if (strcmp(str1, "0"))
        {
            memset(str3, '0', sizeof(str3));
            Add(str1, str2, str3);
            printf("%s\n", str3);
            memset(str3, '0', sizeof(str3));
            Minus(str1, str2, str3);
            printf("%s\n", str3);
            memset(str3, '0', sizeof(str3));
            Mul(str1, str2, str3);
            printf("%s\n", str3);
            memset(str3, '0', sizeof(str3));
            Div(str1, str2, str3);
            printf("%s\n", str3);
        }
        else
        {
            if (strcmp(str2, "0"))
            {
                printf("%s\n-%s\n0\n0\n", str2, str2);
            }
            else
            {
                printf("0\n0\n0\n0\n");
            }
        }
    }
    return 0;
}

void Add(char *str1, char *str2, char *str3)
{   //  str3 = str1 + str2;
    int i, j, i1, i2, tmp, carry;
    int len1 = (int)strlen(str1), len2 = (int)strlen(str2);
    char ch;
    i1 = len1 - 1;
    i2 = len2 - 1;
    j = carry = 0;
    for (; i1 >= 0 && i2 >= 0; ++j, --i1, --i2)
    {
        tmp = str1[i1] - '0' + str2[i2] - '0' + carry;
        carry = tmp / 10;
        str3[j] = tmp % 10 + '0';
    }
    while (i1 >= 0)
    {
        tmp = str1[i1--] - '0' + carry;
        carry = tmp / 10;
        str3[j++] = tmp % 10 + '0';
    }
    while (i2 >= 0)
    {
        tmp = str2[i2--] - '0' + carry;
        carry = tmp / 10;
        str3[j++] = tmp % 10 + '0';
    }
    if (carry)
    {
        str3[j++] = carry + '0';
    }
    str3[j] = '\0';
    for (i = 0, --j; i < j; ++i, --j)
    {
        ch = str3[i];
        str3[i] = str3[j];
        str3[j] = ch;
    }
    return ;
}

void Minus(char *str1, char *str2, char *str3)
{   //  str3 = str1-str2 (str1 > str2)
    int i, j, i1, i2, tmp, carry;
    int len1 = (int)strlen(str1), len2 = (int)strlen(str2);
    char ch;
    i1 = len1 - 1;
    i2 = len2 - 1;
    j = carry = 0;
    while (i2 >= 0)
    {
        tmp = str1[i1] - str2[i2] - carry;
        if (tmp < 0)
        {
            str3[j] = tmp + 10 + '0';
            carry = 1;
        }
        else
        {
            str3[j] = tmp + '0';
            carry = 0;
        }
        i1--;
        i2--;
        j++;
    }
    while (i1 >= 0)
    {
        tmp = str1[i1] - '0' - carry;
        if (tmp < 0)
        {
            str3[j] = tmp + 10 + '0';
            carry = 1;
        }
        else
        {
            str3[j] = tmp + '0';
            carry = 0;
        }
        --i1;
        ++j;
    }
    --j;
    while (str3[j] == '0' && j > 0)
    {
        --j;
    }
    str3[++j] = '\0';
    for (i = 0, --j; i < j; ++i, --j)
    {
        ch = str3[i];
        str3[i] = str3[j];
        str3[j] = ch;
    }
    return ;
}

void Mul(char *str1, char *str2, char *str3)
{
    int i, j = 0, i1, i2, tmp, carry, jj;
    int len1 = (int)strlen(str1), len2 = (int)strlen(str2);
    char ch;
    jj = carry = 0;
    for (i1 = len1 - 1; i1 >= 0; --i1)
    {
        j = jj;
        for (i2 = len2 - 1; i2 >= 0; --i2, ++j)
        {
            tmp = (str3[j] - '0') + (str1[i1] - '0') * (str2[i2] - '0') + carry;
            if (tmp > 9)
            {
                carry = tmp / 10;
                str3[j] = tmp % 10 + '0';
            }
            else
            {
                str3[j] = tmp + '0';
                carry = 0;
            }
        }
        if (carry)
        {
            str3[j] = carry + '0';
            carry = 0;
            j++;
        }
        jj++;
    }
    j--;
    while (str3[j] == '0' && j > 0)
    {
        j--;
    }
    str3[++j] = '\0';
    for (i = 0, --j; i < j; ++i, --j)
    {
        ch = str3[i];
        str3[i] = str3[j];
        str3[j] = ch;
    }
    return ;
}

void Div(char *str1, char *str2, char *str3)
{
    int i1, i2, i, j, jj = 0, tag, carry, cf, c[MAXSIZE];
    int len1 = (int)strlen(str1), len2 = (int)strlen(str2), lend;
    char d[MAXSIZE];
    memset(c, 0, sizeof(c));
    memcpy(d, str1, len2);
    lend = len2;
    j = 0;
    for (i1 = len2 - 1; i1 < len1; ++i1)
    {
        if (lend < len2)
        {
            d[lend] = str1[i1+1];
            c[j] = 0;
            ++j;
            ++lend;
        }
        else if (lend == len2)
        {
            jj = 1;
            for (i = 0; i < lend; ++i)
            {
                if (d[i] > str2[i])
                {
                    break;
                }
                else if (d[i] < str2[i])
                {
                    jj = 0;
                    break;
                }
            }
            if (jj == 0)
            {
                d[lend] = str1[i1+1];
                c[j] = 0;
                ++j;
                ++lend;
                continue;
            }
        }
        if (jj == 1 || lend > len2)
        {
            cf = jj = 0;
            while (d[jj] <= '0' && jj < lend)
            {
                ++jj;
            }
            if (lend - jj > len2)
            {
                cf = 1;
            }
            else if (lend - jj < len2)
            {
                cf = 0;
            }
            else
            {
                i2 = 0;
                cf = 1;
                for (i = jj; i < lend; ++i)
                {
                    if (d[i] < str2[i2])
                    {
                        cf = 0;
                        break;
                    }
                    else if (d[i] > str2[i2])
                    {
                        break;
                    }
                    ++i2;
                }
            }
            while (cf)
            {
                i2 = len2 - 1;
                cf = 0;
                for (i = lend - 1; i >= lend - len2; --i)
                {
                    d[i] = d[i] - str2[i2] + '0';
                    if (d[i] < '0')
                    {
                        d[i] = d[i] + 10;
                        carry = 1;
                        --d[i - 1];
                    }
                    else
                    {
                        carry = 0;
                    }
                    --i2;
                }
                ++c[j];
                jj = 0;
                while (d[jj] <= '0' && jj < lend)
                {
                    ++jj;
                }
                if (lend - jj > len2)
                {
                    cf = 1;
                }
                else if (lend - jj < len2)
                {
                    cf = 0;
                }
                else
                {
                    i2 = 0;
                    cf = 1;
                    for (i = jj; i < lend; ++i)
                    {
                        if (d[i] < str2[i2])
                        {
                            cf = 0;
                            break;
                        }
                        else if (d[i] > str2[i2])
                        {
                            break;
                        }
                        ++i2;
                    }
                }
            }
            jj = 0;
            while (d[jj] <= '0' && jj < lend)
            {
                ++jj;
            }
            for (i = 0; i < lend - jj; ++i)
            {
                d[i] = d[i + jj];
            }
            d[i] = str1[i1 + 1];
            lend = i + 1;
            j++;
        }
    }
    i = tag = 0;
    while (c[i] == 0)
    {
        ++i;
    }
    for (; i < j; ++i, ++tag)
    {
        str3[tag] = c[i]+'0';
    }
    str3[tag] = '\0';
    return ;
}

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