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  1. #include <string>
  2. #include <sstream>
  3. #include <iostream>
  4.  
  5. class Util
  6. {
  7. public:
  8.     std::ostringstream m_os;
  9.  
  10.     Util() {}
  11.     ~Util() { std::cout << m_os.str() << std::endl;}
  12. };
  13.  
  14.  
  15.  
  16. int main (void)
  17. {
  18. // ----------- Using temporary anonymous instance - 
  19.     //  Output does not match expected, and the first insertion seems to
  20.     //  only be able to handle instances that can be converted to int.
  21.  
  22.     // Following prints "97key=val", but expect "akey=val"
  23.     (Util()).m_os << char('a') << std::string("key") << "=" << std::string("val");
  24.  
  25.     // Following prints "0x80491eakey=val", but expect "Plain old C string key=val"
  26.     (Util()).m_os << "Plain old C string " << std::string("key") << "=" << std::string("val");
  27.  
  28.     // Following results in syntax error
  29.     // error: no match for ‘operator<<’ in ‘Util().Util::m_os <<
  30.     (Util()).m_os << std::string("key") << "=" << std::string("val");
  31.  
  32.  
  33. // ----------- Using named instance - output matches expected
  34.  
  35.     // Block results in print "akey=val"
  36.     {
  37.         Util inst;
  38.         inst.m_os  << char('a') << std::string("key") << "=" << std::string("val");
  39.     }
  40.  
  41.     // Block results in print "Plain old C string key=val"
  42.     {
  43.         Util inst;
  44.         inst.m_os  << "Plain old C string " << std::string("key") << "=" << std::string("val");
  45.     }
  46.  
  47.     // Block results in print "key=val"
  48.     {
  49.         Util inst;
  50.         inst.m_os  << std::string("key") << "=" << std::string("val");
  51.     }
  52.  
  53.     return 0;
  54. }
Success #stdin #stdout 0s 3432KB
comments (?)
stdin
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Standard input is empty
stdout
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akey=val
Plain old C string key=val
key=val
akey=val
Plain old C string key=val
key=val
https://ideone.com/IveuCx
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
secret

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