int main()
{
// A definition specifies a variable's type and identifier.
// A definition may also provide an initial value for the object.
// An object defined with a specified first value is spoken of as
// initialized.
//
// C++ supports two form of variable initialization:
// 1) copy-initialization : use equal (=) symbol
// 2) direct-initialization : use parentheses ()
// int ival(1024); // direct-initialization
// int ival = 1023; // copy-initialization
//
// Initialization is NOT assignment!
// Initialization happens when a variable is created and gives that
// variable its initial value.
// Assignment involves obliterating an object's current value and
// replacing that value with a new one.
int demo_direct_initialization(1024);
int demo_copy_initialization = 1024;
// multiple initializer
std::string titleA = "C++ Primer, 4th Ed.";
std::string titleB("C++ Primer, 4th Ed.");
// it is possible to initialize a subsequent variable to the value
// of the value of one defined earlier in the same definition
double salary = 9999.99,
wage(salary + 0.01);
// mix of initialized and uninitialize
int interval, month = 8, day = 7, year = 1955;
// both forms of initialization syntax used
std::string title("C++ Primer, 4th Ed."),
publiser = "A-W";
double price = 109.99, discount = 0.16;
double sale_price = apply_discount(price, discount);
// variables of built-in type defined inside function body
// are uninitialized.
float local_var;
// variables of class types that provide default constructor
// are initialized by the default constructor
std::string empty; // empty is the empty string, empty=""
// some class types do not have a default constructor, every
// definition must provide expicit initializers.
// declaration and definition
// In C++ a variable must be defined exactly once and must be
// defined or declared before it is used.
extern int i; // declares but does not define i
int j; // declares and defines j
// if an initializer is present, the declaration is treated as
// a definition even if the declaration labeled extern, because
// only if it is a defition can it have storage to initialize.
extern double pi = 3.1416; // definition
// Any variable that is used in more than one file requires
// declarations that are seperate from the variable's definition.
// In such cases, one file will contain the definition for the
// variable and other files that use the same variable will contain
// declarations for but not a defition of that same variable.
return 0;
}
TEST(ApplyDiscountTest, apply_discount){
double subtotal = 1.0;
ASSERT_DOUBLE_EQ(apply_discount(subtotal), 0.95);
}
