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Dynamically Allocating Structs | Pointers and Structs
C Structs
course content

Contenido del Curso

C Structs

C Structs

1. Introduction to Structs
2. Pointers and Structs
3. Structs and Memory
4. Advanced Structs Usage
5. Implementing Data Structures

bookDynamically Allocating Structs

Let's review how to dynamically allocate memory in the C language.

To allocate memory on the heap, use the malloc() function from the stdlib.h library:

Note

When you dynamically allocate memory for use in your program, that memory remains reserved until you explicitly free it using free().

c

main

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#include <stdio.h> #include <stdlib.h> // structure definition struct Example { int someValue[20]; // int = 4 bytes, 20 * 4 = 80 bytes }; int main() { // allocating memory for Example structure struct Example* pExample = (struct Example*)malloc(sizeof(struct Example)); printf("Allocating memory = %zu bytes\n", sizeof(*pExample)); // freeing memory free(pExample); return 0; }

If a structure contains several fields of different data types, the compiler will equalize the size of the fields so that the structure is "conveniently" stored in memory.

After the completed job, pay attention to how many bytes are allocated for the structure with the int and char fields. This phenomenon will be discussed later in this course.

Tarea

  1. Create a pointer variable and allocate memory for your structure;
  2. Display the size of structure;
  3. Fill the fields and display the content of your structure;
  4. Free up the allocated memory;
  5. Displaying the values again.

Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
¿Todo estuvo claro?

¿Cómo podemos mejorarlo?

¡Gracias por tus comentarios!

Sección 2. Capítulo 4
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bookDynamically Allocating Structs

Let's review how to dynamically allocate memory in the C language.

To allocate memory on the heap, use the malloc() function from the stdlib.h library:

Note

When you dynamically allocate memory for use in your program, that memory remains reserved until you explicitly free it using free().

c

main

copy
12345678910111213141516171819
#include <stdio.h> #include <stdlib.h> // structure definition struct Example { int someValue[20]; // int = 4 bytes, 20 * 4 = 80 bytes }; int main() { // allocating memory for Example structure struct Example* pExample = (struct Example*)malloc(sizeof(struct Example)); printf("Allocating memory = %zu bytes\n", sizeof(*pExample)); // freeing memory free(pExample); return 0; }

If a structure contains several fields of different data types, the compiler will equalize the size of the fields so that the structure is "conveniently" stored in memory.

After the completed job, pay attention to how many bytes are allocated for the structure with the int and char fields. This phenomenon will be discussed later in this course.

Tarea

  1. Create a pointer variable and allocate memory for your structure;
  2. Display the size of structure;
  3. Fill the fields and display the content of your structure;
  4. Free up the allocated memory;
  5. Displaying the values again.

Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
¿Todo estuvo claro?

¿Cómo podemos mejorarlo?

¡Gracias por tus comentarios!

Sección 2. Capítulo 4
toggle bottom row

bookDynamically Allocating Structs

Let's review how to dynamically allocate memory in the C language.

To allocate memory on the heap, use the malloc() function from the stdlib.h library:

Note

When you dynamically allocate memory for use in your program, that memory remains reserved until you explicitly free it using free().

c

main

copy
12345678910111213141516171819
#include <stdio.h> #include <stdlib.h> // structure definition struct Example { int someValue[20]; // int = 4 bytes, 20 * 4 = 80 bytes }; int main() { // allocating memory for Example structure struct Example* pExample = (struct Example*)malloc(sizeof(struct Example)); printf("Allocating memory = %zu bytes\n", sizeof(*pExample)); // freeing memory free(pExample); return 0; }

If a structure contains several fields of different data types, the compiler will equalize the size of the fields so that the structure is "conveniently" stored in memory.

After the completed job, pay attention to how many bytes are allocated for the structure with the int and char fields. This phenomenon will be discussed later in this course.

Tarea

  1. Create a pointer variable and allocate memory for your structure;
  2. Display the size of structure;
  3. Fill the fields and display the content of your structure;
  4. Free up the allocated memory;
  5. Displaying the values again.

Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
¿Todo estuvo claro?

¿Cómo podemos mejorarlo?

¡Gracias por tus comentarios!

Let's review how to dynamically allocate memory in the C language.

To allocate memory on the heap, use the malloc() function from the stdlib.h library:

Note

When you dynamically allocate memory for use in your program, that memory remains reserved until you explicitly free it using free().

c

main

copy
12345678910111213141516171819
#include <stdio.h> #include <stdlib.h> // structure definition struct Example { int someValue[20]; // int = 4 bytes, 20 * 4 = 80 bytes }; int main() { // allocating memory for Example structure struct Example* pExample = (struct Example*)malloc(sizeof(struct Example)); printf("Allocating memory = %zu bytes\n", sizeof(*pExample)); // freeing memory free(pExample); return 0; }

If a structure contains several fields of different data types, the compiler will equalize the size of the fields so that the structure is "conveniently" stored in memory.

After the completed job, pay attention to how many bytes are allocated for the structure with the int and char fields. This phenomenon will be discussed later in this course.

Tarea

  1. Create a pointer variable and allocate memory for your structure;
  2. Display the size of structure;
  3. Fill the fields and display the content of your structure;
  4. Free up the allocated memory;
  5. Displaying the values again.

Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
Sección 2. Capítulo 4
Switch to desktopCambia al escritorio para practicar en el mundo realContinúe desde donde se encuentra utilizando una de las siguientes opciones
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