{"id":217,"date":"2020-08-31T14:53:24","date_gmt":"2020-08-31T14:53:24","guid":{"rendered":"https:\/\/www.kindsonthegenius.com\/cplusplus\/?p=217"},"modified":"2020-08-31T14:53:24","modified_gmt":"2020-08-31T14:53:24","slug":"c-data-structures","status":"publish","type":"post","link":"https:\/\/www.kindsonthegenius.com\/cplusplus\/c-data-structures\/","title":{"rendered":"C++ Data Structures"},"content":{"rendered":"

In this lesson, we would learn about C++ data structures. We’ll see how to create them and how to use them in programs. We’ll cover the following sub-topics:<\/p>\n

    \n
  1. What are Structures?<\/a><\/li>\n
  2. Declaring a Structure<\/a><\/li>\n
  3. Accessing Members of a Structure<\/a><\/li>\n
  4. Using the typedef<\/em> Keyword<\/a><\/li>\n<\/ol>\n

     <\/p>\n

    1. What are Structures?<\/strong><\/h4>\n

    A structure in C++ is a collection of variables of different data type under a common name. It is similar to a record in a table. So while a C++ Array is a collection of variables of same type, a structure contains variables of different types.<\/p>\n

    Use cases include:<\/p>\n

      \n
    • a student information made up of id, name, admission date, age, and department<\/li>\n
    • a book record consisting of if, title, author and publish date<\/li>\n<\/ul>\n

      You may probably think of other examples as well<\/p>\n

       <\/p>\n

      2. Declaring\u00a0 a Structure<\/strong><\/h4>\n

      Use use the struct<\/strong> <\/em>keyword to define a structure. Specify the struct keyword, followed by an identifier. Then inside curly braces, you can declare all the variables (called members) that make up the structure.<\/p>\n

      For example:
      \n<\/p>\n

      struct<\/span> Student {\r\n\tint<\/span> id;\r\n\tstring firstname;\r\n\tstring lastname;\r\n\tint<\/span> age;\r\n\tstring department;\r\n};\r\n<\/pre>\n
      Here a structure Student<\/strong> <\/em>is defined and is has five members: id, firstname, lastname, age and department.<\/p>\n
      However, when a struct is created, unlike arrays, no memory is allocated. It’s similar to declaring a variable without initialization.<\/p>\n
      After declaring your struct, you can then declare structure type variable in same way you declare other variables. For example<\/p>\n
      Student archana;\r\n<\/pre>\n
      Here, we have declare a variable archana which is of type Student. At this point, the compiler then allocates the required memory.<\/p>\n
       <\/p>\n
      3. Accessing Member Variables of Struct<\/strong><\/h4>\n
      Members of a struct variable are accessed using the member access operator, dot (.)<\/strong>.<\/p>\n
      Assuming we want to access department of structure variable archana and assign a value to it. We can achieve it using<\/p>\n
      <<\/span>struct_name><\/span>.<<\/span>member_name><\/span>\r\n<\/pre>\n
      Like so<\/p>\n
      archana.department =<\/span> \"Computer Science\"<\/span>\r\n<\/pre>\n
      The program below show how a struct works. We define a struct, then assign value from the user input<\/p>\n
      #include <iostream><\/span>\r\n\r\nusing<\/span> namespace<\/span> std;\r\n\r\nstruct<\/span> Student {\r\n\tint<\/span> id;\r\n\tstring firstname;\r\n\tstring lastname;\r\n\tint<\/span> age;\r\n\tstring department;\r\n};\r\n\r\n\/\/ main function<\/span>\r\nint<\/span> main<\/span> () {\r\n\r\n\tStudent archana;\r\n\r\n\tarchana.id =<\/span> 1<\/span>;\r\n\r\n\tcout <<<\/span> \"Enter Student firstname: \"<\/span>;\r\n\tcin>><\/span> archana.firstname;\r\n\tcout <<<\/span> \"Enter Student lastname: \"<\/span>;\r\n\tcin >><\/span> archana.lastname;\r\n\tcout <<<\/span> \"Enter age: \"<\/span>;\r\n\tcin >><\/span> archana.age;\r\n\tcout <<<\/span> \"Enter department: \"<\/span>;\r\n\tcin >><\/span> archana.department;\r\n\r\n\tcout <<<\/span> \"<\/span>\\n<\/span>******* Student Details ********\"<\/span><<<\/span>endl;\r\n\tcout <<<\/span> \"ID:         \"<\/span> <<<\/span> archana.id        <<<\/span>endl;\r\n\tcout <<<\/span> \"Firstname:  \"<\/span> <<<\/span> archana.firstname <<<\/span>endl;\r\n\tcout <<<\/span> \"Lastname:   \"<\/span> <<<\/span> archana.lastname  <<<\/span>endl;\r\n\tcout <<<\/span> \"Age:        \"<\/span> <<<\/span> archana.age       <<<\/span>endl;\r\n\tcout <<<\/span> \"Department: \"<\/span> <<<\/span> archana.department<<<\/span>endl;\r\n\r\n   return<\/span> 0<\/span>;\r\n}\r\n<\/pre>\n
      One thing to note is that the structure is defined outside the main method.<\/p>\n
      The output of this program is given below:<\/p>\n
      Enter Student firstname: Kindson\r\nEnter Student lastname: Munonye\r\nEnter age: 34\r\nEnter department: Computer Science\r\n\r\n******* Student Details ********\r\nID:         1\r\nFirstname:  Kindson\r\nLastname:   Munonye\r\nAge:        34\r\nDepartment: Computer\r\n<\/pre>\n
       <\/p>\n
      4. Using the typedef<\/em> Keyword<\/strong><\/h4>\n
      Another way to create a structure is to use the typedef<\/strong> keyword. This make it kind of easier. For example, the code below creates a student structure.<\/p>\n
      typedef<\/span> struct<\/span> {\r\n\tint<\/span> regNo;\r\n\tstring name;\r\n\tint<\/span> email;\r\n\tstring course;\r\n} Student;\r\n<\/pre>\n
      With this, you can then create Student objects just like before.<\/p>\n
      In addition to creation of structures, the typedef<\/em> <\/strong>keyword can also be used to define variables of other data types. Here are a few examples:
      \n<\/p>\n
      typedef<\/span> long<\/span> int<\/span> myInt; \/\/I just created my own data type!<\/span>\r\n\r\nmyInt x, y; \/\/x any y are now long ints<\/span>\r\n<\/pre>\n
      So this is the much we have for C++ Structures!<\/p>\n","protected":false},"excerpt":{"rendered":"
      In this lesson, we would learn about C++ data structures. We’ll see how to create them and how to use them in programs. We’ll cover … <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[33,34],"class_list":["post-217","post","type-post","status-publish","format-standard","hentry","category-c-tutorials","tag-struct","tag-typedef"],"_links":{"self":[{"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/posts\/217","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=217"}],"version-history":[{"count":3,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/posts\/217\/revisions"}],"predecessor-version":[{"id":220,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/posts\/217\/revisions\/220"}],"wp:attachment":[{"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/media?parent=217"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/categories?post=217"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.kindsonthegenius.com\/cplusplus\/wp-json\/wp\/v2\/tags?post=217"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}