Lära Accessing Struct Fields | Introduction to Structs

After we have created a structure to describe a chemical element, we can finally interact with it.

In order to access the information contained in the structure, we must use the . operator.

The . operator allows us to access the elements (fields) of the structure directly.

<struct>.<field>;

This way we get access to a member of the structure.

Let's try to display information about silicon on the screen:

main.c


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#include "stdio.h"

struct chemicalElement
{
	char name[3];
	int atomicNumber;
	int valency;
	double mass;
};

int main()
{
	struct chemicalElement silicon = { "Si", 14, 4, 28.08 };

	printf("Name: %s\n", silicon.name); 
	printf("Atomic Number: %d\n", silicon.atomicNumber);
	printf("Valency: %d\n", silicon.valency);
	printf("Mass: %f", silicon.mass);

	return 0;
}

Note

Pointers are also widely used to access structure fields, but we'll cover that later.

If you used the second method of creating a struct-variable, you need to use the srtcopy() function to output silicon.name.

main.c


              123456789101112131415161718192021222324
            
#include "stdio.h"

struct chemicalElement
{
	char name[3];
	int atomicNumber;
	int valency;
	double mass;
} silicon;

int main()
{
	strcpy(silicon.name,"Si"); // using `strcpy()`
	silicon.atomicNumber = 14;
	silicon.valency = 4;
	silicon.mass = 28.08;

	printf("Name: %s\n", silicon.name);
	printf("Atomic Number: %d\n", silicon.atomicNumber);
	printf("Valency: %d\n", silicon.valency);
	printf("Mass: %f", silicon.mass);

	return 0;
}

Note

The strcpy() function is used to copy the specified (“Si”) string to the name[3] field of the created variable.

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You have a Product structure that stores information about a product in a store: its name, price, and quantity. Your task is to calculate the total cost of a product by multiplying its price by its quantity.

The function productCost takes a Product as a parameter.

Inside productCost, multiply the price field by the quantity field.
In main, create a Product object with a name, price, and quantity.
Use printf to display the product’s name, price, quantity, and total cost (by calling productCost).

Lösning

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After we have created a structure to describe a chemical element, we can finally interact with it.

In order to access the information contained in the structure, we must use the . operator.

The . operator allows us to access the elements (fields) of the structure directly.

<struct>.<field>;

This way we get access to a member of the structure.

Let's try to display information about silicon on the screen:

main.c


              123456789101112131415161718192021
            
#include "stdio.h"

struct chemicalElement
{
	char name[3];
	int atomicNumber;
	int valency;
	double mass;
};

int main()
{
	struct chemicalElement silicon = { "Si", 14, 4, 28.08 };

	printf("Name: %s\n", silicon.name); 
	printf("Atomic Number: %d\n", silicon.atomicNumber);
	printf("Valency: %d\n", silicon.valency);
	printf("Mass: %f", silicon.mass);

	return 0;
}

Note

Pointers are also widely used to access structure fields, but we'll cover that later.

If you used the second method of creating a struct-variable, you need to use the srtcopy() function to output silicon.name.

main.c


              123456789101112131415161718192021222324
            
#include "stdio.h"

struct chemicalElement
{
	char name[3];
	int atomicNumber;
	int valency;
	double mass;
} silicon;

int main()
{
	strcpy(silicon.name,"Si"); // using `strcpy()`
	silicon.atomicNumber = 14;
	silicon.valency = 4;
	silicon.mass = 28.08;

	printf("Name: %s\n", silicon.name);
	printf("Atomic Number: %d\n", silicon.atomicNumber);
	printf("Valency: %d\n", silicon.valency);
	printf("Mass: %f", silicon.mass);

	return 0;
}

Note

The strcpy() function is used to copy the specified (“Si”) string to the name[3] field of the created variable.

Uppgift

Swipe to start coding

The function productCost takes a Product as a parameter.

Inside productCost, multiply the price field by the quantity field.
In main, create a Product object with a name, price, and quantity.
Use printf to display the product’s name, price, quantity, and total cost (by calling productCost).

Lösning

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Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 1. Kapitel 5

single