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  1. #include <iostream>
  2. using std::cout;
  3. using std::endl;
  4.  
  5. #include <cstring>
  6.  
  7. struct String
  8. {
  9.     char    *buf;
  10.     size_t  len;
  11.  
  12.     String()
  13.     {
  14.         len = 0U;
  15.         buf = new char[1U];
  16.  
  17.         *buf = '\0';
  18.     }
  19.  
  20.     String( const char *cstr )
  21.     {
  22.         len = strlen( cstr );
  23.  
  24.         buf = new char[len + 1U];
  25.  
  26.         memcpy( buf, cstr, len + 1U );
  27.     }
  28.  
  29.     String( const String &str )
  30.     {
  31.         len = str.length();
  32.  
  33.         buf = new char[len + 1U];
  34.  
  35.         memcpy( buf, str.buf, len + 1U );
  36.     }
  37.  
  38.     String &operator=( const String &rhs )
  39.     {
  40.         if( this != &rhs )
  41.         {
  42.             this->~String();
  43.  
  44.             len = rhs.length();
  45.  
  46.             buf = new char[len + 1U];
  47.  
  48.             memcpy( buf, rhs.buf, len + 1U );
  49.         }
  50.  
  51.         return *this;
  52.     }
  53.  
  54.     String operator+( const String &rhs ) const
  55.     {
  56.         String  tmp;
  57.  
  58.         tmp.~String();
  59.  
  60.         tmp.len = this->length() + rhs.length();
  61.         tmp.buf = new char[tmp.len + 1U];
  62.  
  63.         memcpy( tmp.buf, this->buf, this->length() + 1U );
  64.         strcat( tmp.buf, rhs.buf );
  65.  
  66.         return tmp;
  67.     }
  68.  
  69.     size_t length() const
  70.     {
  71.         return len;
  72.     }
  73.  
  74.     ~String()
  75.     {
  76.         delete [] buf;
  77.  
  78.         len = 0U;
  79.     }
  80. };
  81.  
  82.  
  83. int main()
  84. {
  85.     String  s1( "123" );
  86.     String  s2;
  87.     String  s3 = s1 + s2 + "789";
  88.     String  s4;
  89.  
  90.     s2 = "456";
  91.     s4 = s3 + "0";
  92.  
  93.     cout << s1.buf << endl;
  94.     cout << s2.buf << endl;
  95.     cout << s3.buf << endl;
  96.     cout << s4.buf << endl;
  97.  
  98.     return 0;
  99. }
  100.  
Success #stdin #stdout 0s 3028KB
comments (?)
stdin 
Standard input is empty
stdout 
123
456
123789
1237890
https://ideone.com/WFyfqm
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
public

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