C Structure

Abstract

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typedef struct {
  int acctNum;
  float balance;
} account_t;

• C structures allow us to define custom data types, enabling us to group variables of different types under a single name
• This above code snippet defines a structure type named account_t

Structure variables

Structure variables have memory allocated to them. Using the code snippet above, we can create structure variables using account_t a_1, a_2; which creates two structure variables a_1 and a_2.

Initialising structure variables

Using the code snippet above, we can initialise the structure variable with account_t a_1 = {1, 955.9};

Accessing members of structure variables

Using the code snippet above, we can access and modify the balance using a_1.balance;

Dereferencing a pointer to a structure and accessing its attributes

We need to make sure we use parentheses like (*player_ptr).name, because . has a higher operator precedence.

Or we can simply use player_ptr->name to achieve the same, this is a syntactic sugar.

C Union

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union _union_name_ {
    _datatype member1_;
    _datatype member2_;
    ...
};

• The Union is a user-defined data type in C language that can contain elements of the different data types just like structure. But unlike structures, all the members in the C union are stored in the same memory location. Due to this, only one member can store data at the given instance

What can we do with this?

We can efficiently obtain the representation of the same element in different data type encodings.

Enum

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enum Heat {
  LOW,
  MEDIUM,
  HIGH
}

• A C type that represents a group integer constants that can’t be changed

Benefits

This improves code readability and prevents bugs.

References

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• C Unions - GeeksforGeeks