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Advanced Classes and Objects Part III
Part III Using swap When using moveFrom , if a new data member is added, both swap and moveFrom have to be modified. To avoid that, one can write the move constructor and move assignment operator with a default constructor and the swap function. class Bank { private : Bank ( ) = default ; } Now cleanup() and moveFrom() can be removed. The destructor handles the code from cleanup . The code is as follows: Bank :: Bank ( Bank && src ) noexcept : Bank ( ) { swap ( * this , src ) ; //Default constructor creates *this. } Bank & Bank :: operator = ( Bank && rhs ) noexcept { Bank temp ( std :: move ( rhs ) ) //Need std::move because rhs is named swap ( * this , temp ) ; return * this ; } Implementing swap with move semantics Using move semantics improves the performance of swap as seen below: void swa...
C++ strings and string_view
C-style strings C style strings should be avoided except when interfacing with C libraries. C string library functions provide no bounds checking and memory allocation support. They are represented as an array of characters. Last character of the string is the null character \0 , so that code that uses the string knows where it ends. The space needed for a string is always one more than the number of readable characters. String Literals Strings written with quotes around them are string literals. They are stored in a read-only part of memory. Because they are stored in readonly sections, attempting to modify string literals is undefined behavior . Example: char * str = "world" ; str [ 0 ] = 'y' ; //undefined behavior If the code respected the standard and assigned the string literal to const char* , the compiler will catch attempts to modify string literals: const char * str = "world" ; str [ 0 ] = 'k' ; //compiler will f...
C++ Tour Part I
C++ Tour Hello World Here is the hello world program for C++: # include <iostream> int main ( ) { std :: cout << "Hello, World" << std :: endl ; return 0 ; } Building a C++ Program Building a C++ program is a three step process: Code is run through preprocessor which processes meta information The code is compiled where each .cpp file is translated to .o object file Individual object files are linked together into a single application. Main function Main function is where program execution starts. It comes in two flavors: with and without arguments. With arguments, it looks as follows: int main ( int argc , char * argv [ ] ) where argc gives the number of commandline arguments to the program, and argv array contains those arguments. The actual arguments start from index 1. I/O Streams cout is the stream for standard output, cerr is the strea...
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