Example Code

• Code for in-class discussion

Character arrays (C-style strings)

• C-style string is a character array that ends with the null character (different than
   

  nullptr
  )
• null character literal is
   

  '\0'
• character literals are put in single quotes
• •  

    'a', '\n', '$'
• string literals are put in double quotes
• •  

    "Hello\n"
• Examples:
  
   

  char msg[] = "Hello\n";
  
  Note that the above is equivalent to:
  
   

  char msg[] = 'H', 'e', 'l', 'l', 'o', '\n', '\0';
• the null-character is implicitly a part of any string literal; it provides an indirect means to determine a character array's size

Dynamic memory allocation

•  

  new
  operator can be used to dynamically allocate memory
• Syntax —
   

  new
  followed by the type being allocated new int; // dynamically allocates an int new double; // dynamically allocates a double
  AخA

   

  new int; // dynamically allocates an int

  new double; // dynamically allocates a double
•  

  delete
  operator deallocates memory allocated using
   

  new
• lifetime of allocations indicated by
   

  new
  and
   

  delete
  not by scope (e.g., memory allocated inside a function is still valid outside the function)
• creating an array with
   

  new
  — put brackets with a size after the type // allocates an array of 40 ints new int[40]; // note that the size can be a variable // allocates an array of size doubles new double[size];
   

  // allocates an array of 40 ints

  new int[40];

  // note that the size can be a variable

  // allocates an array of size doubles

  new double[size];
• These statements above are not very useful by themselves, because the allocated spaces have no names! BUT, the new operator returns the starting address of the allocated space, and this address can be stored in a pointer: int* p; // declare a pointer p p = new int; // dynamically allocate an int and load address into p double* d; // declare a pointer d d = new double; // allocate a double and store address into d // we can also do these in single line statements int x = 40; int* list = new int[x]; float* numbers = new float[x+10];
  ​x

   

  int* p; // declare a pointer p

  p = new int; // dynamically allocate an int and load address into p

  ​

  double* d; // declare a pointer d

  d = new double; // allocate a double and store address into d

  ​

  // we can also do these in single line statements

  int x = 40;

  int* list = new int[x];

  float* numbers = new float[x+10];

Additional Examples

• binary and linear search