Md Shoriful Islam Ashiq

  Initializing multiple variables In the last section, we noted that it is possible to define multiple variables  of the same type  in a single statement by separating the names with a comma: int a , b ; COPY We also noted that best practice is to avoid this syntax altogether. However, since you may encounter other code that uses this style, it’s still useful to talk a little bit more about it, if for no other reason than to reinforce some of the reasons you should be avoiding it. You can initialize multiple variables defined on the same line: int a = 5 , b = 6 ; // copy initialization int c ( 7 ) , d ( 8 ) ; // direct initialization int e { 9 } , f { 10 } ; // brace initialization (preferred) COPY Unfortunately, there’s a common pitfall here that can occur when the programmer mistakenly tries to initialize both variables by using one initialization statement: int a , b = 5 ; // wrong (a is not initialized!) int a = 5 , b = 5 ; // correct COPY In the t

  Value initialization and zero initialization When a variable is initialized with empty braces,  value initialization  takes place. In most cases,  value initialization  will initialize the variable to zero (or empty, if that’s more appropriate for a given type). In such cases where zeroing occurs, this is called  zero initialization . int width { } ; // zero initialization to value 0 COPY Q: When should I initialize with { 0 } vs {}? Use an explicit initialization value if you’re actually using that value. int x { 0 } ; // explicit initialization to value 0 std :: cout << x ; // we're using that zero value COPY Use value initialization if the value is temporary and will be replaced. int x { } ; // value initialization std :: cin >> x ; // we're immediately replacing that value COPY Initialize your variables Initialize your variables upon creation. You may eventually find cases where you want to ignore this advice for a specific reason (e.g. a perform

  Initialization One downside of assignment is that it requires at least two statements: one to define the variable, and one to assign the value. These two steps can be combined. When a variable is defined, you can also provide an initial value for the variable at the same time. This is called  initialization . The value used to initialize a variable is called an  initializer . Initialization in C++ is surprisingly complex, so we’ll present a simplified view here. There are 4 basic ways to initialize variables in C++: int a ; // no initializer int b = 5 ; // initializer after equals sign int c ( 6 ) ; // initializer in parenthesis int d { 7 } ; // initializer in braces COPY You may see the above forms written with different spacing (e.g.  int d{7}; ). Whether you use extra spaces for readability or not is a matter of personal preference. Default initialization When no initialization value is provided (such as for variable  a  above), this is called  default initializati