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  1. #include <iostream>
  2. #include <cstring>
  3.  
  4. using namespace std;
  5.  
  6. int main(void)
  7. {
  8.     char *buffer = NULL;
  9.     size_t bufferSize = 0;
  10.     size_t count = 0;
  11.     char c;
  12.  
  13.     while(cin.get(c) && c != '\n')
  14.     {
  15.         // Resize the buffer if we need more space.
  16.         if(count + 2 > bufferSize) // bufferSize includes null terminator.
  17.         {
  18.             // Store information about the original one.
  19.             char *old = buffer;
  20.             size_t oldSize = bufferSize;
  21.  
  22.             // Calculate new size.
  23.             bufferSize = ((count + 2) / 5 + 1) * 5;
  24.             cout << "current length : " << count << "  new size : " << bufferSize << endl;
  25.  
  26.             // Allocate using new size.
  27.             buffer = new char[bufferSize];
  28.  
  29.             // Copy from the old one.
  30.             memcpy(buffer, old, oldSize);
  31.  
  32.             delete [] old;
  33.         }
  34.  
  35.         buffer[count] = c;
  36.         ++count;
  37.     }
  38.  
  39.     // Add null terminator.
  40.     buffer[count] = '\0';
  41.  
  42.     cout << buffer << endl;
  43.  
  44.     return 0;
  45. }
Success #stdin #stdout 0.01s 2860KB
comments (?)
stdin
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Hello world!
stdout
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current length : 0  new size : 5
current length : 4  new size : 10
current length : 9  new size : 15
Hello world!
https://ideone.com/al3r0D
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
secret

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