We already know that data is stored in memory. So variables allow you to name the storage for your data. Therefore, you as a programmer can create variables.<\/p>\n
Each variable must have a specific data type. (you can review data types<\/a>). The data type determines the size of the variable. That is the size of memory it occupies.<\/p>\n To name a variable, there are some rule to follow:<\/p>\n Examples of variables are: score, student, num1, _var<\/p>\n <\/p>\n Variable Types<\/strong><\/p>\n This is about the same as Data Types<\/a>. The basic types of variables in C++ are listed below:<\/p>\n Stores either value true or false.<\/td>\n<\/tr>\n Typically a single octet (one byte). This is an integer type.<\/td>\n<\/tr>\n The most natural size of integer for the machine.<\/td>\n<\/tr>\n A single-precision floating point value.<\/td>\n<\/tr>\n A double-precision floating point value.<\/td>\n<\/tr>\n Represents the absence of type.<\/td>\n<\/tr>\n A wide character type.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n <\/p>\n Now, the types in the list above is also known as primitive types. However, C++ also provides other types of variables. These include:<\/p>\n We would examine these in subsequent lessons<\/p>\n <\/p>\n <\/p>\n Before you can use a variable, you must define it. This simply means you provide a name of the variable, then you provide the data type as well. In this way, the compiler reserves the right amount of space for the variable.<\/p>\n Examples of how to define a variable is given below:<\/p>\n <\/p>\n <\/p>\n Initializing a Variable<\/strong><\/p>\n This means assigning an initial value to the variable. This can be done along with the declaration. It could also be done\u00a0 in another line. The code below declares and initialized the same variables.<\/p>\n <\/p>\n <\/p>\n If however, you declare a variable without initializing it, then the value is set to NULL for static storage. For others, the value is undefined. So it’s always good to declare your variables.<\/p>\n <\/p>\n Why Variables are Declared<\/strong><\/p>\n Declared variables reduces the compilation time. This is because, the compiler knows that there is a variable of the specified type, then linking can proceed.<\/p>\n Also, when multiple files are used, then variable define in one file would be available in another file. This happens during the linking phase.<\/p>\n However for this to work, you need to declare the variable using the extern keyword. This you do in just one place.<\/p>\n <\/p>\n Declaration vs Definition Example<\/strong><\/p>\n The example below illustrates the difference between variable declaration and definition.<\/p>\n <\/p>\n If you run the code above, then you will have the output:<\/p>\n <\/p>\n <\/p>\n You probably will hear of these only in C++!<\/p>\n Lvalues and Rvalues are the two types of expressions in C++. So what are they?<\/p>\n For example:<\/p>\n <\/p>\n <\/p>\n <\/p>\n Variables are rvalues and therefore can appear on any side of an assignment statement. However, literals like numbers are lvalues.<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" We already know that data is stored in memory. So variables allow you to name the storage for your data. Therefore, you as a programmer … <\/p>\n","protected":false},"author":1,"featured_media":40,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[10,9],"class_list":["post-39","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-c-tutorials","tag-lvalue-and-rvalue","tag-variables"],"_links":{"self":[{"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/posts\/39","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/comments?post=39"}],"version-history":[{"count":3,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/posts\/39\/revisions"}],"predecessor-version":[{"id":47,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/posts\/39\/revisions\/47"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/media\/40"}],"wp:attachment":[{"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/media?parent=39"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/categories?post=39"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/tags?post=39"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\n
\n\n
\n S.No<\/th>\n Type and brief Description<\/th>\n<\/tr>\n \n 1<\/td>\n bool<\/b><\/p>\n \n 2<\/td>\n char<\/b><\/p>\n \n 3<\/td>\n int<\/b><\/p>\n \n 4<\/td>\n float<\/b><\/p>\n \n 5<\/td>\n double<\/b><\/p>\n \n 6<\/td>\n void<\/b><\/p>\n \n 7<\/td>\n wchar_t<\/b><\/p>\n \n
Defining and Initializing a Variable<\/strong><\/h4>\n
int<\/span> a, b c; \/\/declares the variables a, b, c as int<\/span>\r\nfloat<\/span> score; \/\/declares the variables score as float<\/span>\r\nchar<\/span> grade; \/\/declares the variables grade as char<\/span>\r\ndouble<\/span> amount, salary; \/\/declares the variables amount and salary as double<\/span>\r\n<\/pre>\nint<\/span> a =<\/span> 10<\/span>, b =<\/span> 20<\/span>, c =<\/span> 30<\/span>; \r\nfloat<\/span> score =<\/span> 99.3<\/span>; \r\nchar<\/span> grade 'A'<\/span>; \r\ndouble<\/span> amount 8000<\/span>, salary =<\/span> 25000<\/span>;\r\n<\/pre>\n\/\/Variable declaration vs definition<\/span>\r\n\/\/By Kindson The Genius<\/span>\r\n#include <iostream><\/span>\r\nusing<\/span> namespace<\/span> std;\r\n\r\n\/\/ Variable declarations:<\/span>\r\nextern<\/span> int<\/span> x, y;\r\nextern<\/span> int<\/span> z;\r\nextern<\/span> float<\/span> w;\r\n \r\nint<\/span> main<\/span> () {\r\n \/\/ Variable definitions:<\/span>\r\n int<\/span> x, y;\r\n int<\/span> z;\r\n float<\/span> w;\r\n \r\n \/\/ initialization<\/span>\r\n x =<\/span> 10<\/span>;\r\n y =<\/span> 20<\/span>;\r\n z =<\/span> x +<\/span> y;\r\n \r\n cout <<<\/span> z <<<\/span> endl ;\r\n\r\n w =<\/span> 70.0<\/span>\/<\/span>3.0<\/span>;\r\n cout <<<\/span> w <<<\/span> endl ;\r\n \r\n return<\/span> 0<\/span>;\r\n}\r\n<\/pre>\n30<\/span>\r\n23.333<\/span>\r\n<\/pre>\nLvalues and Rvalues<\/strong><\/h4>\n
\n
int<\/span> age;\r\nage =<\/span> 37<\/span>; \/\/ age is and lvalue, 37 is an rvalue<\/span>\r\n<\/pre>\n