C++ Primer 5th Edition Reading Notes

Dealing with Types type alias typedef double wages; // wages is a synonym for double typedef wages base, *p; // base is a synonym for double, p for double* C++11: alias declaration using SI = Sales_item; // SI is a synonym for Sales_item As usual, a const that appears in the base type modifies the given type. The type of pstring is “pointer to char.” So, const pstring is a constant pointer to char—not a pointer to const char. It can be tempting, albeit incorrect, to interpret a declaration that uses a type alias by conceptually replacing the alias with its corresponding type. typedef char *pstring; const pstring cstr = 0; // cstr is a constant pointer to char const pstring *ps; // ps is a pointer to a constant pointer to char const char *cstr = 0; // wrong interpretation of const pstring cstr C++11: auto. auto tells the compiler to deduce the type from the initializer. The initializers for all the variables in the declaration using auto must have types that a...

const Qualifier Because we can’t change the value of a const object after we create it, it must be initialized just as reference const int i = get_size(); // ok: initialized at run time const int j = 42; // ok: initialized at compile time const int k; // error: k is uninitialized const when we use an object to initialize another object, it doesn’t matter whether either or both of the objects are consts. int i = 42; const int ci = i; // ok: the value in i is copied into ci int j = ci; // ok:the value in ci is copied into j By Default, const Objects Are Local to a File When we really need to share const between files, define a single instance of a const variable, we use the keyword extern on both its definition and declaration(s). // file_1.cc defines and initializes a const that is accessible to other files extern const int bufSize = fcn(); // file_1.h extern const int bufSize; // same bufSize as defined in file_1.cc References to const const int ci = 102...

Compound Types References Reference is not an object. It is an alias. It is just another name for an already existing object. int ival = 1024; int &refVal = ival; //refVal referes to (is another name for) ival int &refVal2; // error: a reference must be initialized When we define a reference, instead of copying the initializer's value, we bind the reference to its initializer. Once initialized, a reference remains bound to its initial object. There is no way to rebind a reference to refer to a different object. Because there is no way to rebind a reference, references must be initialized. When we assign to a reference, we are assigning to the object to which the reference is bound. int i = refVal; //OKay i= 1024 Because references are not objects, we may not define a reference to a reference. We can define multiple references in a single definition. Each identifier that is a reference must be preceded by the & symbol: int ...

Primitive Build-in Types void type arithmetic type: bool, char, wchar_t, char16_t, char32_t, short, int, long, long long, float, double, long double Literals 'a' // character literal "Hello World!" // string literal L'a' // wide character literal, type is wchar_t u8"hi!" // utf-8 string literal (utf-8 encodes a Unicode character in 8 bits) 42ULL // unsigned integer literal, type is unsigned long long 1E-3F // single-precision floating-point literal, type is float 3.14159L // extended-precision floating-point literal, type is long double Variables Initialization is not assignment. Initialization happens when a variable is given a value when it is created. Assignment obliterates an object’s current value and replaces that value with a new one. Four different ways to define an int variable named units_sold and initialize it to 0. int units_sold = 0; int units_sold = {0}; int units_sold{0}; int units_sold(0); When used with va...

Different compilers use different suffix conventions; the most common include .cc , .cxx , .cpp , .cp , and .C .  To compile: $ CC prog1.cc prog1.exe is generated on Windows, a.out is generated on UNIX To run: $prog1 or $.\prog1 The command used to run the C++ compiler varies across compilers and operating systems. $ g++ -o prog1 prog1.cc Depending on the release of the GNU compiler you are using, you may need to specify -std=c++0x to turn on C++ 11 support. Typically, we put all the #include directives for a program at the beginning of the source file. std::cout << "Enter two numbers:" << std::endl;  Our output statement uses the << operator twice. Because the operator returns its left-hand operand, the result of the first operator becomes the left-hand operand of the second.    Equivalent to: (std::cout << "Enter two numbers:") << std::end;   ...