随机产生1~100以内的加减运算题，要求用户输入答案，然后系统显示出正确答案

要实现这个功能，我们可以使用C++编写一个简单的控制台程序。这里我会提供一个基本的示例，包括生成随机数、计算答案以及获取用户的输入。我们将用到`<iostream>`（输入输出流）和`<cstdlib>`（包含`rand()`和`srand()`函数）库。

首先，我们需要设置随机数种子：

#include <iostream>
#include <cstdlib>

// ... (后续代码)
std::srand(std::time(0)); // 设置随机数种子，保证每次运行结果不同

接下来，我们生成两个1到100之间的随机整数用于加减运算：

int num1 = std::rand() % 100 + 1;
int num2 = std::rand() % 100 + 1;

然后选择一个随机操作符（加或减）：

int operator_choice = rand() % 2; // 0代表加法，1代表减法
char op;
if (operator_choice == 0) {
    op = '+';
} else {
    op = '-';
}

现在我们构造题目并获取用户的输入：

std::cout << "What is the result of " << num1 << " " << op << " " << num2 << "? ";
std::cin >> answer;

最后，我们检查用户的答案是否正确，并给出结果：

int correct_answer;
if (op == '+') {
    correct_answer = num1 + num2;
} else { // 减法
    correct_answer = num1 - num2;
}

if (answer == correct_answer) {
    std::cout << "Correct!" << std::endl;
} else {
    std::cout << "Incorrect, the correct answer is " << correct_answer << "." << std::endl;
}

完整代码如下：

#include <iostream>
#include <cstdlib>

int main() {
    std::srand(std::time(0)); // 设置随机数种子

    int num1 = std::rand() % 100 + 1;
    int num2 = std::rand() % 100 + 1;

    int operator_choice = rand() % 2;
    char op;
    if (operator_choice == 0) {
        op = '+';
    } else {
        op = '-';
    }

    int answer;
    std::cout << "What is the result of " << num1 << " " << op << " " << num2 << "? ";
    std::cin >> answer;

    int correct_answer;
    if (op == '+') {
        correct_answer = num1 + num2;
    } else {
        correct_answer = num1 - num2;
    }

    if (answer == correct_answer) {
        std::cout << "Correct!" << std::endl;
    } else {
        std::cout << "Incorrect, the correct answer is " << correct_answer << "." << std::endl;
    }
    
    return 0;
}