CSCE 121 Chapter 4

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Objects, types, and values

complex<int> = z(1, 2);  // ordered pairs

Type Safety

• object will only be used according to its type
• static type safety checks types at compilation
• dynamic type safety checks types at runtime

C++ is not completely statically/dynamically type-safe

EX:

int main() {
  int a = 20000;
  char c = a;    // squeezing a big int into a 1 byte value
  int b = c;     // getting the int value of c

  return 0;
}

Auto-initialization is "random" — always assign to initial value

Computation

• Abstractions: we know that it works, and that's all we want to know
• Algorithms work well, and we know why they work well (we can prove it)
  • A logical arithmetical or computational procedure that, if correctly applied, ensures the solution of a problem
• Heuristics work well in practice, but we don't know why

Vectors

Code:

vector<int> nums;
nums.push_back(1);

// OR

vector<char> alphabet(26);

// OR

vector<bool> lights(3, true);

Monday, September 6, 2010

cin can be read into vector:

vector<double> temps;
double temp;
while (cin >> temp) temps.push_back(temp);

Built-in functions

size()

The number of elements in the vector

begin()

The first item of a vector

end()

The last item of a vector

begin() and end() are good for sorting:

sort(v.begin(), v.end())

push_back(item)

Add item to the end of an array.