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  1. #include <iostream>
  2. #include <ctime>
  3. #include <string>
  4. #include <sstream>
  5. #include <stdexcept>
  6. // #include <sys/time.h>
  7.  
  8. // invariant: time_str contains today's local wall clock time in the form 'hh:mm:ss'
  9. std::time_t str_to_time_t( const std::string& time_str )
  10. {
  11.     constexpr char COLON = ':' ;
  12.     enum { UB_HR = 24, UB_MIN = 60, UB_SEC = 60 };
  13.  
  14.     char delimiter ;
  15.     const std::time_t now = std::time(nullptr) ;
  16.     std::tm tm = *std::localtime( &now );
  17.  
  18.     std::istringstream stm(time_str) ;
  19.     if( ( stm >> tm.tm_hour && tm.tm_hour >= 0 && tm.tm_hour < UB_HR ) &&
  20.         ( stm >> delimiter && delimiter == COLON ) &&
  21.         ( stm >> tm.tm_min && tm.tm_min >= 0 && tm.tm_min < UB_MIN ) &&
  22.         ( stm >> delimiter && delimiter == COLON ) &&
  23.         ( stm >> tm.tm_sec && tm.tm_sec >= 0 && tm.tm_sec < UB_SEC ) &&
  24.         ( stm >> std::ws && stm.eof() ) )
  25.     {
  26.         return std::mktime(&tm) ;
  27.     }
  28.     else throw std::invalid_argument( "invalid time string" ) ;
  29. }
  30.  
  31. int main() // minimal test driver
  32. {
  33.     const std::string test[] = { "2:34:6", "19:74:55", "12x18y0", "23:59:59", "12:0:0" } ;
  34.     for( const std::string& s : test )
  35.     {
  36.         try
  37.         {
  38.             const std::time_t time_to_set = str_to_time_t(s) ;
  39.             const std::tm tm = *std::localtime( &time_to_set );
  40.             char cstr[128] ;
  41.             std::strftime( cstr, sizeof(cstr), "%A, %Y %B %d %H:%M:%S", &tm ) ;
  42.             std::cout << cstr << " (" << time_to_set << ")\n" ;
  43.             // const time_val tv { time_to_set, 0 } ;
  44.             // settimeofday( &t, nullptr ) ;
  45.         }
  46.         catch( const std::exception& )
  47.         {
  48.             std::cerr << "badly formed time string '" << s << "'\n" ;
  49.         }
  50.     }
  51. }
  52.  
Success #stdin #stdout #stderr 0s 3432KB
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stdin
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Standard input is empty
stdout
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Sunday, 2013 September 15 02:34:06 (1379212446)
Sunday, 2013 September 15 23:59:59 (1379289599)
Sunday, 2013 September 15 12:00:00 (1379246400)
stderr
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badly formed time string '19:74:55'
badly formed time string '12x18y0'
https://ideone.com/0prtOt
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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