Single Structures in C

6 Key excerpts on "Single Structures in C"

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  eBook - ePub

  Learn C Programming

  A beginner's guide to learning C programming the easy and disciplined way

  • Jeff Szuhay(Author)
  • 2020(Publication Date)
  • Packt Publishing

    (Publisher)

  Creating and Using Structures When a number of values all pertain to a single thing, we can keep them organized with structures. A structure is a user-defined type. There may be multiple values in a structure and they may be of the same type or different types. A structure, then, is a collection of information representing a complex object. With structures, not only can we represent complex objects more realistically, but we can also create functions that manipulate the structure in relevant ways. Just like data within a structure is grouped together in a meaningful manner, we can also group functions that manipulate the structure together in meaningful ways. C is not an object-oriented programming (OOP) language. However, OOP has been a primary focus of programming languages and programming since the early 1990s. It is extremely likely that after you learn C, you will, at the very least, be exposed to object-oriented programming concepts. Therefore, after we learn about C structures and the operations we can use on them, we will learn how C structures are a logical transition to OOP

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  eBook - PDF

  Data Structures with C Programming

  • Anil Kumar Yadav, Vinod Kumar Yadav(Authors)
  • 2019(Publication Date)
  • Arcler Press

    (Publisher)

  DATA STRUCTURES 1 CHAPTER CONTENTS 1.1. Introduction ........................................................................................ 2 1.2. Data Structure Basic Terminology ....................................................... 2 1.3. Data Structure ..................................................................................... 3 1.4. Introduction To Algorithm ................................................................... 8 1.5. Basic Concept of Function ................................................................ 13 1.6. Basic Concept of Pointers ................................................................. 19 1.7. Introduction To Structure ................................................................... 22 1.8. Dynamic Memory Allocation In Data Structure ................................. 28 Data Structures with C Programming 2 1.1. INTRODUCTION In the Computer Programming or Software development, Data Structures is one of the most valuable roles for computer engineers. Use of appropriate data structures enables a computer system to perform its task more efficiently, by influencing the ability of computers to store and retrieve data from any location in its memory. A data structure is a method of how storing data on a computer so that it can be used efficiently. In Computer Programming we are using different types of data to perform, store, access and sent data and information. Computers cannot do without data, so organizing that data is very important. If that data is not organized effectively, it is very difficult to perform any task on that data. If it is organized effectively then any operation can be performed easily on that data. 1.2. DATA STRUCTURE BASIC TERMINOLOGY 1.2.1. Data and Data Types Data are a group of specific facts, numbers, character, and figures. A data item refers to a single unit of values. Data is an unprocessed form of information.

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  eBook - ePub

  ANSI C Programming

  Learn ANSI C step by step

  • Yashavant Kanetkar(Author)
  • 2020(Publication Date)
  • BPB Publications

    (Publisher)

  12 Structures

  • Why Use Structures Declaring a Structure Accessing Structure Elements How Structure Elements are Stored
  • Array of Structures
  • Additional Features of Structures
  • Uses of Structures
  • Summary
  • Exercise

   

  W hich mechanic is good enough who knows how to repair only one type of vehicle? None. Same thing is true about C language. It wouldn’t have been so popular had it been able to handle only all int s, or all float s or all char s at a time. In fact, when we handle real world data, we don’t usually deal with little atoms of information by themselves—things like integers, characters and such. Instead, we deal with entities that are collections of things, each thing having its own attributes, just as the entity we call a ‘book’ is a collection of things such as title, author, call number, publisher, number of pages, date of publication, etc. As you can see, all this data is dissimilar, for example, author is a string, whereas number of pages is an integer. For dealing with such collections, C provides a data type called ‘structure’. A structure gathers together, different atoms of information that comprise a given entity. And structure is the topic of this chapter.

  Why Use Structures

  We have seen earlier how ordinary variables can hold one piece of information and how arrays can hold a number of pieces of information of the same data type. These two data types can handle a great variety of situations. But quite often we deal with entities that are collection of dissimilar data types.

  For example, suppose you want to store data about a book. You might want to store its name (a string), its price (a float) and number of pages in it (an int). If data about say 3 such books is to be stored, then we can follow two approaches:

  (a) Construct individual arrays, one for storing names, another for storing prices and still another for storing number of pages. (b) Use a structure variable. Let us examine these two approaches one by one. For the sake of programming convenience, assume that the names of books would be single character long. Let us begin with a program that uses arrays.

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  eBook - ePub

  Learn C Programming from Scratch

  A step-by-step methodology with problem solving approach (English Edition)

  • Mohammad Saleem Mir(Author)
  • 2024(Publication Date)
  • BPB Publications

    (Publisher)

  HAPTER 7Structures and Unions Introduction

  In this chapter, we will explore structures and unions in the C programming language. Structures allow us to define custom data types that can hold multiple variables of different types. Unions, on the other hand, enable us to allocate memory that can be interpreted in multiple ways. We will learn how to create and access members of structures and unions effectively.

  Structure In this chapter, we will cover the following topics:

  • Structures
  • Unions
  • User-defined data types
  • Enumerations
  • Members of structure/unions
  • Accessing structure/union members

  Objectives

  The objective of this chapter is to provide a comprehensive understanding of structures and unions in C. By the end of this chapter, we aim to equip you with the knowledge and skills necessary to create and manipulate structures and unions. You will learn how to define structures to hold related data and access their members. Additionally, you will understand the concept of unions and how to access their different interpretations of memory.

  Structures and unions In C programming, structures, and unions are used to group multiple variables of different data types.

  A structure, usually referred to as a struct, is a grouping of variables of various data kinds that are given a single name. A struct’s members are all its variables, and they may all be accessed using the dot notation, as in structName, memberName .

  Complex data types, such as a date or a point in three dimensions, can be represented via structures.

  For instance, the code below creates a structure called student with three members named Roll_No , nm , and marks :

  struct student { int Roll_No; char nm[20]; float marks; };

  A union is similar to a struct, except for the fact that all members of a union share the common memory location. This means that the value of one member will overwrite the value of another member if the union is not set to the correct member. Unions are typically used when you want to conserve the memory space by using a single block of memory to store multiple variables of different types, but only one of them is used at a time.

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  eBook - ePub

  Ivor Horton's Beginning Visual C++ 2008

  • Ivor Horton(Author)
  • 2011(Publication Date)
  • Wrox

    (Publisher)

  struct s in this chapter before exploring the more extensive capabilities offered by classes.

  What Is a struct?

  Almost all the variables that you have seen up to now have been able to store a single type of entity—a number of some kind, a character, or an array of elements of the same type. The real world is a bit more complicated than that, and just about any physical object you can think of needs several items of data to describe it even minimally. Think about the information that might be needed to describe something as simple as a book. You might consider title, author, publisher, date of publication, number of pages, price, topic or classification, and ISBN number just for starters, and you can probably come up with a few more without too much difficulty. You could specify separate variables to contain each of the parameters that you need to describe a book, but ideally you would want to have a single data type, BOOK say, which embodied all of these parameters. I'm sure you won't be surprised to hear that this is exactly what a struct can do for you.

  Defining a struct

  Let's stick with the notion of a book, and suppose that you just want to include the title, author, publisher, and year of publication within your definition of a book. You could declare a structure to accommodate this as follows:

  struct BOOK { char Title[80]; char Author[80]; char Publisher[80]; int Year; };

  This doesn't define any variables, but it actually creates a new type for variables and the name of the type is BOOK . The keyword struct defines BOOK as such, and the elements making up an object of this type are defined within the braces. Note that each line defining an element in the struct is terminated by a semicolon, and that a semicolon also appears after the closing brace. The elements of a struct can be of any type, except the same type as the struct being defined. You couldn't have an element of type BOOK included in the structure definition for BOOK , for example. You may think this to be a limitation, but note that you could include a pointer to a variable of type BOOK

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  eBook - PDF

  Low-Level Programming

  C, Assembly, and Program Execution on Intel® 64 Architecture

  • Igor Zhirkov(Author)
  • 2017(Publication Date)
  • Apress

    (Publisher)

  A structure is a data type which packs several fields. Each field is a variable of its own type. Mathematics would probably be happy calling structures “tuples with named fields.” To create a variable of a structural type we can refer to the example shown in Listing 9-38 . There we define a variable d which has two fields: a and b of types int and char , respectively. Then d.a and d.b become valid expressions that you can use just as you are using variable names. Listing 9-38. struct_anon.c struct { int a; char b; } d; d.a = 0; d.b = 'k'; This way, however, you only create a one-time structure. In fact, you are describing a type of d but you are not creating a new named structural type. The latter can be done using a syntax shown in Listing 9-39 . CHAPTER 9 ■ TYPE SYSTEM 168 Listing 9-39. struct_named.c struct pair { int a; int b; }; ... struct pair d; d.a = 0; d.b = 1; Be very aware that the type name is not pair but struct pair , and you can not omit the struct keyword without confusing the compiler. The C language has a concept of namespaces quite different from the namespaces in other languages (including C++). There is a global type namespace, and then there is a tag-namespace, shared between struct , union , and enum datatypes. The name following the struct keyword is a tag. You can define a structural type whose name is the same as other type, and the compiler will distinguish them based on the struct keyword presence. An example shown in Listing 9-40 demonstrates two variables of types struct type and type , which are perfectly accepted by the compiler. Listing 9-40. struct_namespace.c typedef unsigned int type; struct type { char c; }; int main( int argc, char** argv ) { struct type st; type t; return 0; } It does not mean, though, that you really should make types with similar names. However, as struct type is a perfectly fine type name, it can be aliased as type using the typedef keyword, as shown in Listing 9-41 .

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