C++ cin 与 C sscanf

发布于 2024-12-12 11:04:08 字数 267 浏览 0 评论 0原文

所以我用 C 写了这个，所以 sscanf 扫描 s 但然后丢弃它，然后扫描 d 并存储它。因此，如果输入是“Hello 007”，则会扫描 Hello 但将其丢弃，并将 007 存储在 d 中。

static void cmd_test(const char *s)
{
    int d = maxdepth;
    sscanf(s, "%*s%d", &d);
}

所以，我的问题是如何在 C++ 中做同样的事情？可能使用字符串流？

原文

So i wrote this in C, so sscanf scans in s but then discards it, then scans in d and stores it. So if the input is "Hello 007", Hello is scanned but discarded and 007 is stored in d.

static void cmd_test(const char *s)
{
    int d = maxdepth;
    sscanf(s, "%*s%d", &d);
}

So, my question is how can I do the same thing but in C++? possibly using stringstream?

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内心激荡 2024-12-19 11:04:08

#include <string>
#include <sstream>

static void cmd_test(const char *s)
{
    std::istringstream iss(s);
    std::string dummy;
    int d = maxdepth;
    iss >> dummy >> d;
}

#include <string>
#include <sstream>

static void cmd_test(const char *s)
{
    std::istringstream iss(s);
    std::string dummy;
    int d = maxdepth;
    iss >> dummy >> d;
}

回复收藏 0 原文

世俗缘 2024-12-19 11:04:08

您无法真正提取到匿名字符串，但您可以创建一个虚拟字符串并忽略它：

#include <string>
#include <istream>
// #include <sstream> // see below

void cmd_test(std::istream & iss) // any std::istream will do!
{

  // alternatively, pass a `const char * str` as the argument,
  // change the above header inclusion, and declare:
  // std::istringstream iss(str);

  int d;
  std::string s;

  if (!(iss >> s >> d)) { /* maybe handle error */ }

  // now `d` holds your value if the above succeeded
}

请注意，提取可能会失败，因此我输入了条件。发生错误时由您决定； C++ 要做的事情是抛出异常（尽管如果您的实际函数已经传达错误，您可能只能返回一个错误）。

用法示例：

#include <iostream>
#include <fstream>

int main()
{
  cmd_test(std::cin);

  std::ifstream infile("myfile.txt");
  cmd_test(infile);

  std::string s = get_string_from_user();
  std::istringstream iss(s);
  cmd_test(iss);
}

You can't really extract into an anonymous string, but you can just make a dummy and ignore it:

#include <string>
#include <istream>
// #include <sstream> // see below

void cmd_test(std::istream & iss) // any std::istream will do!
{

  // alternatively, pass a `const char * str` as the argument,
  // change the above header inclusion, and declare:
  // std::istringstream iss(str);

  int d;
  std::string s;

  if (!(iss >> s >> d)) { /* maybe handle error */ }

  // now `d` holds your value if the above succeeded
}

Note that the extraction might fail, whence the conditional I put in. It's up to you what you do in case of an error; the C++ thing to do would be to throw an exception (though if your actual function communicates errors already, you might be able to just return an error).

Example usage:

#include <iostream>
#include <fstream>

int main()
{
  cmd_test(std::cin);

  std::ifstream infile("myfile.txt");
  cmd_test(infile);

  std::string s = get_string_from_user();
  std::istringstream iss(s);
  cmd_test(iss);
}

回复收藏 0 原文

孤城病女 2024-12-19 11:04:08

怎么样：

#include <string>
#include <sstream>

static void cmd_test(const std::string &s)
{
    int d = maxdepth;
    std::string dont_care;
    std::istringstream in(s);
    in >> dont_care >> d;
}

What about:

#include <string>
#include <sstream>

static void cmd_test(const std::string &s)
{
    int d = maxdepth;
    std::string dont_care;
    std::istringstream in(s);
    in >> dont_care >> d;
}

回复收藏 0 原文

~没有更多了~