Comprehensive Study Notes on C++ Structs and Data Management

Comparison of Data Types: Array vs. Struct

• Arrays are used for variables containing data that share the same data type. An example provided is $int\,marks[10]$, which stores 10 integer values.

• Structs (Structures) are used for variables that encompass different data types within a single entity. Examples include grouping $int\,credit$ and $float\,cgpa$ together.

• Memory Allocation and Declaration:

  • For standard types like $int$, $float$, and $char$, as well as arrays, memory is allocated in the computer during declaration.
  • Example: $int\,mark;$ allocates a single integer space.
  • Example: $int\,mark[2];$ allocates two adjacent spaces labeled $mark[0]$ and $mark[1]$.

Struct Definition and Declaration Protocols

• To allocate memory for a struct, both a definition and a declaration are required.

• Struct Definition Syntax:

  • A struct is defined with the keyword $struct$ followed by a name (e.g., $CourseInfo$).
  • The structural members are placed inside curly braces.
  • Example:     $struct\,CourseInfo\,\{\dots\};$

• Defining the $CourseInfo$ Structure:

  • Members include:
  • $string\,name$
  • $string\,code$
  • $int\,credit$

• Struct Declaration:

  • Once defined, you can declare instances of that struct.
  • Example: $CourseInfo\,Course1;$ and $CourseInfo\,Course2;$

• Combined Definition and Declaration Syntax:

  • A struct can be defined and declared simultaneously by placing variable names after the closing brace but before the semicolon.
  • Example:     $struct\,\{\,string\,name;\,string\,code;\,int\,credit;\,\}\,Course1,\,Course2;$

Initialization and Member Access

• Initialization of a Struct:

  • Data can be assigned to a struct using curly braces in chronological order of the definition.
  • Example: $CourseInfo\,Course1 = \{"Structured\,Programming",\,"MTS3013",\,3\};$

• Member Access Operators:

  • Arrays use indexes or subscripts (e.g., $[i]$).
  • Structs use the Dot Operator or Member Access Operator ($.$).
  • Example: $Course1.name$ refers to the name member of the $Course1$ instance.

Core Operations on Structs

• Assignment (Input Data):

  • Values can be assigned directly to specific members.
  • Example:
  • $Course1.name = "Data\,Struct";$
  • $Course1.code = "MTS3023";$
  • $Course1.credit = 3;$

• Standard Input ($cin$):

  • Members can be populated via user input.
  • Example:
  • $cin >> Course1.name;$
  • $cin >> Course1.code;$
  • $cin >> Course1.credit;$

• Standard Output ($cout$):

  • Members are displayed using the dot operator.
  • Example:
  • $cout << Course1.name;$
  • $cout << Course1.code;$
  • $cout << Course1.credit;$

Dynamic Variables and Memory Management

• Dynamic variables are constructed during the execution of a program ($a/c$).

• $new$ Keyword:

  • Used to build a new temporary variable by allocating a memory location indicated by a pointer.

• $delete$ Keyword:

  • Used to destroy a previously built dynamic variable by removing that specific memory location.

Practical Exercises and Scenario-Based Coding

• Question 1: Car Information Management

  • Structure Definition:
  • $struct\,car\,\{\,char\,no\_plat[9];\,char\,name[40];\,int\,year;\,double\,price;\,\};$
  • Task (i): Declare a single instance named $car1$.
  • Solution: $car\,car1;$
  • Task (ii): Declare an array named $list$ for 20 cars.
  • Solution: $car\,list[20];$
  • Task (iii): Write input statements for both.
  • For $car1$: Uses standard $cin$ flow for all four members.
  • For $list$: Uses a $for$ loop where $x$ ranges from $0$ to $19$, accessing $list[x].member\,name$.

• Question 2: Camera Database Application

  • Structure Definition: Includes $cameraMake$, $cameraModel$, $zoomLevel$, $megaPixels$, and $price$.
  • Task (a): Declare an array for 25 cameras.
  • Solution: $Camera\,Camera1[25];$
  • Task (b): Segment for inputting data.
  • Uses a loop with variable $y$ from $0$ to $24$ to input data for each cataloged camera.
  • Task (c): Filter display based on price.
  • Logic: $if\,(Camera1[y].price > 500)\,\{\,cout << Camera1[y].cameraModel;\,\}$

• Question 3: Info_Kad Debit Card Records

  • Structure Definition: $string\,name$, $int\,no\_kad$, $int\,year$.
  • Task (a): Declare $kad\_debit$ for 10 customers.
  • Solution: $Info\_Kad\,kad\_debit[10];$
  • Task (b): Main function for input/output.
  • Utilizes two separate $for$ loops (typically using index $i$) to carry out sequential input and output for all 10 records.

• Question 4: Staff Personal Records

  • Structure Definition ($Personal\_Rekod$):
  • $string\,namaTerakhir$ (Last Name)
  • $string\,namaPertama$ (First Name)
  • $int\,umur$ (Age)
  • Task (a): Declaration for 10 staffs.
  • Solution: $Personal\_Rekod\,staf[10];$
  • Task (b): Implement main function to manage academic staff.
  • Solution includes prompts: "Masukkan nama Pertama", "Masukkan nama Terakhir", and "Masukkan umur".
  • The output combines both names and the age in one line: $cout << ahli\_akademik[i].namaPertama << " " << ahli\_akademik[i].namaTerakhir << " " << ahli\_akademik[i].umur;$