从字符串c ++中读取所有整数 [英] Read all integers from string c++

问题描述

我需要一些帮助来获取std :: string中的所有整数并将每个整数转换为int变量。

I need some help with getting all the integers from a std::string and getting each of those integer into an int variable.

字符串示例：

<blah> hi 153 67 216

我希望程序忽略blah和hi并存储每个整数变成一个int变量。所以它就像是：

I would like the program to ignore the "blah" and "hi" and store each of the integers into an int variable. So it comes out to be like:

a = 153
b = 67
c = 216

然后我可以单独自由打印，如：

Then i can freely print each separately like:

printf("First int: %d", a);
printf("Second int: %d", b);
printf("Third int: %d", c);

谢谢！

推荐答案

您可以使用 scan_is 创建自己的函数来操作 std :: ctype facet方法。然后，您可以将生成的字符串返回到 stringstream 对象，并将内容插入到整数中：

You can create your own function that manipulates a std::ctype facet by using its scan_is method. Then you can return the generated string to a stringstream object and insert the contents to your integers:

#include <iostream>
#include <locale>
#include <string>
#include <sstream>
#include <algorithm>
#include <iterator>
#include <cstring>

std::string extract_ints(std::ctype_base::mask category, std::string str, std::ctype<char> const& facet)
{
    using std::strlen;

    char const *begin = &str.front(),
               *end   = &str.back();

    auto res = facet.scan_is(category, begin, end);

    begin = &res[0];
    end   = &res[strlen(res)];

    return std::string(begin, end);
}

std::string extract_ints(std::string str)
{
    return extract_ints(std::ctype_base::digit, str,
         std::use_facet<std::ctype<char>>(std::locale("")));
}

int main()
{
    int a, b, c;

    std::string str = "abc 1 2 3";
    std::stringstream ss(extract_ints(str));

    ss >> a >> b >> c;

    std::cout << a << '\n' << b << '\n' << c;
}

输出：

Output:

1
2
3

1 2 3

演示

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