How to perform data verification in C++ code?

How to perform data verification in C code?

When writing C code, data verification is a very important part. By verifying the data entered by the user, the robustness and security of the program can be enhanced. This article will introduce some common data verification methods and techniques to help readers effectively verify data in C code.

1. Input data type check
   Before processing the data input by the user, first check whether the type of the input data meets the requirements. For example, if you need to receive integer input from the user, you need to ensure that the user input is a legal integer. This can be checked using C's input stream object (std::cin) and the appropriate type variable.

int num;
std::cout << "请输入一个整数: ";
std::cin >> num;
if(std::cin.fail()) {
    std::cout << "输入错误！请输入一个整数。" << std::endl;
    std::cin.clear();
    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '
');
    // 清除输入缓冲区，避免死循环
} else {
    // 继续处理输入数据
}

2. Input data range check
   In addition to checking the type of input data, you also need to check whether the input data is within a reasonable range. For example, for a certain numeric input, you need to make sure it is within a certain range. Range checking can be done using conditional statements or loop structures.

int age;
std::cout << "请输入您的年龄: ";
std::cin >> age;
if(age < 0 || age > 150) {
    std::cout << "年龄不合法！请重新输入。" << std::endl;
} else {
    // 继续处理输入数据
}

3. Data format check
   Sometimes it is necessary to check the format of the input data to ensure the correctness and consistency of the data. For example, for date input, you can use regular expressions (regex) in the C standard library for format checking.

#include <regex>

std::string date;
std::cout << "请输入日期(格式: yyyy-mm-dd): ";
std::cin >> date;
std::regex datePattern("^\d{4}-\d{2}-\d{2}$"); // 定义日期格式的正则表达式
if(!std::regex_match(date, datePattern)) {
    std::cout << "日期格式错误！请按照指定格式输入。" << std::endl;
} else {
    // 继续处理输入数据
}

4. Data integrity check
   Before processing the data entered by the user, the integrity of the data needs to be checked to ensure that necessary data is not missing. For example, for form input, you need to ensure that all required fields are filled in.

std::string name, email, password;
std::cout << "请输入用户名: ";
std::cin >> name;
std::cout << "请输入邮箱: ";
std::cin >> email;
std::cout << "请输入密码: ";
std::cin >> password;

if(name.empty() || email.empty() || password.empty()) {
    std::cout << "信息不完整！请填写完整的信息。" << std::endl;
} else {
    // 继续处理输入数据
}

5. Exception handling
   When processing input data, if you encounter an abnormal situation (such as file read and write errors, memory allocation failure, etc.), you need to capture and handle the exception. to ensure the normal operation of the program.

try {
    // 可能会抛出异常的代码
} catch (const std::exception& e) {
    std::cout << "发生异常: " << e.what() << std::endl;
}

In summary, data verification of C code is very important and can be achieved through type checking, range checking, format checking, integrity checking and exception handling. Proper use of these verification methods can effectively improve the reliability and security of the program. I hope this article can provide some help to readers in data verification of C code.

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