c语言：长整数1输入、长整数2输入、长整数输出、加法、减法、除法、退出系统

好的，以下是 C 语言实现长整数输入、输出、加减除法和退出系统的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define N 200 // 数字串的最大长度

// 枚举运算符类型
typedef enum { ADD, SUB, MUL, DIV } Operator;

// 倒置字符串
void reverse(char* str, int len) {
    int i = 0, j = len - 1;
    while (i < j) {
        char temp = str[i];
        str[i] = str[j];
        str[j] = temp;
        i++;
        j--;
    }
}

// 去掉前导零
void removeLeadingZero(char* str) {
    int len = strlen(str);
    int i = 0;
    while (i < len - 1 && str[i] == '0') {
        i++;
    }
    if (i > 0) {
        for (int j = i; j < len; j++) {
            str[j - i] = str[j];
        }
        str[len - i] = '\0';
    }
}

// 长整数加法
char* add(char* num1, char* num2) {
    int len1 = strlen(num1), len2 = strlen(num2);
    int len = len1 > len2 ? len1 : len2;
    char* result = (char*)malloc(sizeof(char) * (len + 2)); // 多分配一位用于存放进位
    memset(result, '0', len + 1);
    result[len + 1] = '\0';
    reverse(num1, len1);
    reverse(num2, len2);
    for (int i = 0; i < len; i++) {
        int n1 = i < len1 ? num1[i] - '0' : 0;
        int n2 = i < len2 ? num2[i] - '0' : 0;
        int sum = result[i] - '0' + n1 + n2;
        result[i] = sum % 10 + '0';
        result[i + 1] += sum / 10;
    }
    reverse(result, len + 1);
    removeLeadingZero(result);
    return result;
}

// 长整数减法
char* sub(char* num1, char* num2) {
    int len1 = strlen(num1), len2 = strlen(num2);
    int len = len1 > len2 ? len1 : len2;
    char* result = (char*)malloc(sizeof(char) * (len + 1));
    int borrow = 0;
    reverse(num1, len1);
    reverse(num2, len2);
    for (int i = 0; i < len; i++) {
        int n1 = i < len1 ? num1[i] - '0' : 0;
        int n2 = i < len2 ? num2[i] - '0' : 0;
        int diff = n1 - n2 - borrow;
        if (diff < 0) {
            diff += 10;
            borrow = 1;
        } else {
            borrow = 0;
        }
        result[i] = diff + '0';
    }
    reverse(result, len);
    removeLeadingZero(result);
    return result;
}

// 长整数乘法
char* mul(char* num1, char* num2) {
    int len1 = strlen(num1), len2 = strlen(num2);
    int len = len1 + len2 + 1;
    char* result = (char*)malloc(sizeof(char) * (len + 1));
    memset(result, '0', len);
    result[len] = '\0';
    reverse(num1, len1);
    reverse(num2, len2);
    for (int i = 0; i < len1; i++) {
        for (int j = 0; j < len2; j++) {
            int n1 = num1[i] - '0', n2 = num2[j] - '0';
            int mul = n1 * n2 + result[i + j] - '0';
            result[i + j] = mul % 10 + '0';
            result[i + j + 1] += mul / 10;
        }
    }
    reverse(result, len);
    removeLeadingZero(result);
    return result;
}

// 长整数除法
char* div(char* num1, char* num2) {
    int len1 = strlen(num1), len2 = strlen(num2);
    if (len2 == 1 && num2[0] == '0') {
        return NULL;
    }
    if (len1 < len2 || (len1 == len2 && strcmp(num1, num2) < 0)) {
        char* result = (char*)malloc(sizeof(char) * 2);
        result[0] = '0';
        result[1] = '\0';
        return result;
    }
    int len = len1 - len2 + 2;
    char* result = (char*)malloc(sizeof(char) * (len + 1));
    memset(result, '0', len);
    result[len] = '\0';
    char* temp = (char*)malloc(sizeof(char) * (len1 + 1));
    memset(temp, '0', len1 + 1);
    temp[len1] = '\0';
    strncpy(temp, num1, len2);
    for (int i = len2 - 1; i < len1; i++) {
        int quotient = 0;
        while (strcmp(temp, num2) >= 0) {
            quotient++;
            char* diff = sub(temp, num2);
            strcpy(temp, diff);
            free(diff);
        }
        result[i - len2 + 2] = quotient + '0';
        temp[i + 1] = num1[i + 1];
    }
    removeLeadingZero(result);
    free(temp);
    return result;
}

int main() {
    char num1[N], num2[N];
    while (1) {
        printf("请选择操作：\n");
        printf("1. 长整数加法\n");
        printf("2. 长整数减法\n");
        printf("3. 长整数乘法\n");
        printf("4. 长整数除法\n");
        printf("5. 退出系统\n");
        int op;
        scanf("%d", &op);
        if (op == 5) {
            break;
        }
        printf("请输入第一个长整数：");
        scanf("%s", num1);
        printf("请输入第二个长整数：");
        scanf("%s", num2);
        char* result;
        switch (op) {
            case 1:
                result = add(num1, num2);
                printf("结果为：%s\n", result);
                free(result);
                break;
            case 2:
                result = sub(num1, num2);
                printf("结果为：%s\n", result);
                free(result);
                break;
            case 3:
                result = mul(num1, num2);
                printf("结果为：%s\n", result);
                free(result);
                break;
            case 4:
                result = div(num1, num2);
                if (result == NULL) {
                    printf("除数不能为0！\n");
                } else {
                    printf("结果为：%s\n", result);
                    free(result);
                }
                break;
            default:
                printf("无效操作！\n");
                break;
        }
    }
    printf("感谢使用！\n");
    return 0;
}

该程序实现了长整数的加减乘除四种基本运算，并提供了退出系统的选项。用户可以根据提示输入操作和操作数，程序会输出对应的结果。需要注意的是，该程序假设输入的长整数都是非负整数。