字符串解析指定的格式

String Parse for a specific format

本文关键字：格式 字符串      更新时间：2023-10-16

string = std::vector<int>(6,0)，并希望它显示为{ 0 0 0 0 0 0 }

I tried this 

#include <iostream>
using namespace std;

int main()
{
    string str = "std::vector<int>(6,0)" ;
    unsigned found = str.find('(');
    char c = str[found+1];
    int i = c - '0'; 
    char ch = str[found+3];
    int j = ch - '0';
    str = "{ ";
    for(int k = 0; k < i ; k++)
    {
        str = str + ch + " " ;
    }
    str = str + " }";
    cout << str << endl; 
    return 0;
}

它工作，但看起来不是很有效。有更好的主意吗?

当前版本的代码只适用于向量大小和元素大小的个位数值。使用std::stringstream作为更好的解决方案:

#include <iostream>
#include <sstream>
using namespace std;

int main()
{
  string str = "std::vector<int>(6,0)" ;
  unsigned found = str.find('(');
  string arguments = str.substr(found);
  // Replace non-numeric chars with spaces.
  for (unsigned i=0;i<arguments.size(); ++i) {
    if (!isdigit(arguments[i])) {
      arguments[i] = ' ';
    }
  }
  std::istringstream iss(arguments);
  int size;
  // String to avoid having to cast later on
  string value;
  iss >> size >> value;
  string res = "{;
  for (int i = 0; i < size; ++i) {
    res += " " + value;
  }
  res += " }";
  cout << res;
  return 0;
}

下面是代码的另一个版本(希望)更灵活一些。它找到"("先"，然后")"，用逗号分隔它们，去掉所有空白字符并将数字转换为整数。然后打印出来。

#include <string>
#include <iostream>
using namespace std;
//these three functions are taken from here: 
//http://stackoverflow.com/questions/216823/whats-the-best-way-to-trim-stdstring
#include <algorithm> 
#include <functional> 
#include <cctype>
#include <locale>
static inline std::string &ltrim(std::string &s) {
        s.erase(s.begin(), std::find_if(s.begin(), s.end(), std::not1(std::ptr_fun<int, int>(std::isspace))));
        return s;
}
// trim from end
static inline std::string &rtrim(std::string &s) {
        s.erase(std::find_if(s.rbegin(), s.rend(), std::not1(std::ptr_fun<int, int>(std::isspace))).base(), s.end());
        return s;
}
// trim from both ends
static inline std::string &trim(std::string &s) {
        return ltrim(rtrim(s));
}
int main()
{
    string s = "std::vector<int>(612,30)";
    int paren_start = s.find("(")+1;
    string numbers = s.substr(paren_start, s.find(")")-paren_start);
    int comma_pos = numbers.find(",");
    string first_num = numbers.substr(0, comma_pos);
    string second_num = numbers.substr(comma_pos+1, numbers.size()-comma_pos);
    int first = atoi(trim(first_num).c_str());
    int second = atoi(trim(second_num).c_str());
    cout << "{" << endl;
    for(int i=0; i<first; i++)
    {
        cout << second << " ";
    }
    cout << "}" << endl;
    return 0;
}
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