strtok或std :: istringstream

Question

我有下面的代碼，它使用strtok從txt文件接收輸入。在TXT文件中的輸入是：

age, (4, years, 5, months) 
age, (8, years, 7, months) 
age, (4, years, 5, months) 

我的代碼如下所示：

char * point; 
ifstream file; 
file.open(file.c_str()); 

if(file.is_open()) 
{ 
    while(file.good()) 
    { 
     getline(file, take); 
     point = strtok(&take[0], ",()"); 
    } 
} 

它做精不同的是二次歲的輸出和第三年齡缺失。誰能告訴我他們爲什麼失蹤？

此外，我試圖istringstream但每當我輸入我的文件名程序崩潰。

char * point; 
char take[256]; 
ifstream file; 
file.open(file.c_str()); 

if(file.is_open()) 
{ 
    while(file.good()) 
    { 
     cin.getline(take, 256); 
     point =strtok(take,",()"); 
    } 
} 

Answer 1

就個人而言，我會用一個std::istringstream但我想不同的使用它（...，是的，我知道，我可以用sscanf()以及與該代碼會短一些，但我不喜歡的類型 - 不安全的界面）！我會玩與操縱器的技巧：

#include <iostream> 
#include <sstream> 
#include <string> 

template <char C> 
std::istream& skip(std::istream& in) 
{ 
    if ((in >> std::ws).peek() != std::char_traits<char>::to_int_type(C)) { 
     in.setstate(std::ios_base::failbit); 
    } 
    return in.ignore(); 
} 

std::istream& (*const comma)(std::istream&) = &skip<','>; 
std::istream& (*const open)(std::istream&) = &skip<'('>; 
std::istream& (*const close)(std::istream&) = &skip<')'>; 

struct token 
{ 
    token(std::string const& value): value_(value) {} 
    std::string::const_iterator begin() const { return this->value_.begin(); } 
    std::string::const_iterator end() const { return this->value_.end(); } 
    std::string value_; 
}; 

std::istream& operator>> (std::istream& in, token const& t) 
{ 
    std::istreambuf_iterator<char> it(in >> std::ws), end; 
    for (std::string::const_iterator sit(t.begin()), send(t.end()); 
     it != end && sit != send; ++it, ++sit) { 
     if (*it != *sit) { 
      in.setstate(std::ios_base::failbit); 
      break; 
     } 
    } 
    return in; 
} 

int main() 
{ 
    std::istringstream input("age, (4, years, 5, months)\n" 
          "age , (8 , years , 7, months)\n" 
          "age, (4, year, 5, months)\n" 
          "age, (4, years 5, months)\n" 
          "age (4, years, 5, months)\n" 
          "age, 4, years, 5, months)\n" 
          "age, (4, years, 5, months)\n"); 
    std::string dummy; 
    int   year, month; 
    for (std::string line; std::getline(input, line);) { 
     std::istringstream lin(line); 
     if (lin >> token("age") >> comma 
      >> open 
      >> year >> comma >> token("years") >> comma 
      >> month >> comma >> token("months") >> close) { 
      std::cout << "year=" << year << " month=" << month << "\n"; 
     } 
    } 
}