从 C++ 中的文件中读取整数和字符的混合；

发布于 2024-10-31 19:34:18 字数 765 浏览 1 评论 0原文

我在用 C++ 读取文件时遇到一些问题。我只能读取整数或字母。但我无法同时读取两者，例如 10af、ff5a。我的过程如下：

int main(int argc, char *argv[]) {

if (argc < 2) {
    std::cerr << "You should provide a file name." << std::endl;
    return -1;
}

std::ifstream input_file(argv[1]);
if (!input_file) {
    std::cerr << "I can't read " << argv[1] << "." << std::endl;
    return -1;
}

std::string line;
for (int line_no = 1; std::getline(input_file, line); ++line_no) {
    //std::cout << line << std::endl;

         -----------
    }
       return 0;
 }

所以我想做的是，我允许用户指定他想要读取的输入文件，并且我使用 getline 来获取每一行。我可以使用标记方法来仅读取整数或仅读取字母。但我无法同时阅读两者。如果我的输入文件是

2 1 89ab

8 2 16ff

读取此文件的最佳方法是什么？

预先非常感谢您的帮助！

原文

I have some trouble with reading of a file in C++. I am able to read only integers or only alphabets. But I am not able to read both for example, 10af, ff5a. My procedure is as follows:

int main(int argc, char *argv[]) {

if (argc < 2) {
    std::cerr << "You should provide a file name." << std::endl;
    return -1;
}

std::ifstream input_file(argv[1]);
if (!input_file) {
    std::cerr << "I can't read " << argv[1] << "." << std::endl;
    return -1;
}

std::string line;
for (int line_no = 1; std::getline(input_file, line); ++line_no) {
    //std::cout << line << std::endl;

         -----------
    }
       return 0;
 }

So what I am trying to do is, I am allowing the user to specify the input file he wants to read, and I am using getline to obtain each line. I can use the method of tokens to read only integers or only alphabets. But I am not able to read a mix of both. If my input file is

2 1 89ab

8 2 16ff

What is the best way to read this file?

Thanks a lot in advance for your help!

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鹿! 2024-11-07 19:34:18

我会使用 std::stringstream，并且从 89ab 和 16ff 开始使用 std::hex看起来像十六进制数字。

应如下所示：

std::string line;
for (int line_no = 1; std::getline(input_file, line); ++line_no)
{
    std::stringstream ss(line);
    int a, b, c;

    ss >> a;
    ss >> b;
    ss >> std::hex >> c;
 }

您需要 #include

I'd use a std::stringstream, and use std::hex since 89ab and 16ff look like hex numbers.

Should look like this:

std::string line;
for (int line_no = 1; std::getline(input_file, line); ++line_no)
{
    std::stringstream ss(line);
    int a, b, c;

    ss >> a;
    ss >> b;
    ss >> std::hex >> c;
 }

You will need to #include <sstream>

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蛮可爱 2024-11-07 19:34:18

使用

std::string s;
while (input_file >> s) {
  //add s to an array or process s
  ...
}

您可以读取 std::string 类型的输入，它可以是数字和字母的任意组合。您不一定需要逐行读取输入，然后尝试解析它。 >> 运算符将空格和换行符视为分隔符。

Using

std::string s;
while (input_file >> s) {
  //add s to an array or process s
  ...
}

you can read inputs of type std::string which could be any combination of digits and alphabets. You don't necessarily need to read input line by line and then try to parse it. >> operator considers both space and newline as delimiters.

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