C Programming/Structs
Objectiveedit
|
LessoneditIntroductioneditStructures allow objects of different types to be stored within one object. Let's say that you want to store a car's colour, maximum speed and registration number. We can define a structure that includes all that information. First, include the header files required for #include <stdio.h>
#include <string.h>
Define the structure: struct car
{
unsigned int colour;
unsigned int max_speed;
char reg_num[10];
};
Example of the structure being used: int main(void)
{
/* define two car objects */
struct car car_1, car_2;
car_1.colour = 1; /* initialize car_1's colour */
car_1.max_speed = 200; /* initialize car_1's speed */
/* initialize the reg number */
strcpy(car_1.reg_num, "MG 100");
/* copy car_1 data to car_2 */
car_2 = car_1;
/* print the values */
printf("Colour = %u\n", car_2.colour);
printf("Speed = %u\n", car_2.max_speed);
printf("Reg = %s\n", car_2.reg_num);
return 0;
}
Dynamic StructureseditAlong with being static, structures can also be dynamic. This means that they can be created and deleted at run time. An example is given below. #include <stdio.h>
// This is a basic dog structure.
struct dog
{
char *name;
char *breed;
char *coat;
int age;
};
// Describes the dog.
void describe(struct dog *d)
{
printf("This is a %s dog. The %s's name is %s. %s has a nice %s coat. %s is %d years old.\n\n",
d->breed, d->breed, d->name, d->name, d->coat, d->name, d->age);
}
int main(void)
{
// Allocate memory for all of the dogs.
// Notice that size for malloc is struct dog and it's casted as struct dog*.
struct dog *dog1 = (struct dog*) malloc(sizeof(struct dog));
struct dog *dog2 = (struct dog*) malloc(sizeof(struct dog));
struct dog *dog3 = (struct dog*) malloc(sizeof(struct dog));
// Give the dogs some personality.
dog1->name = "Foxtrot";
dog1->breed = "American Eskimo";
dog1->coat = "white";
dog1->age = 6;
dog2->name = "Delta";
dog2->breed = "German Shepherd";
dog2->coat = "tan with a black saddle";
dog2->age = 3;
dog3->name = "Whiskey";
dog3->breed = "Tamaskan";
dog3->coat = "wolf grey";
dog3->age = 2;
// Tell the user about each dog.
describe(dog1);
describe(dog2);
describe(dog3);
// Free the allocated memory.
free(dog1);
free(dog2);
free(dog3);
return 0;
}
OUTPUT This is a American Eskimo dog. The American Eskimo's name is Foxtrot. Foxtrot has a nice white coat. Foxtrot is 6 years old. This is a German Shepherd dog. The German Shepherd's name is Delta. Delta has a nice tan with a black saddle coat. Delta is 3 years old. This is a Tamaskan dog. The Tamaskan's name is Whiskey. Whiskey has a nice wolf grey coat. Whiskey is 2 years old. It is now possible to do dynamic things with each |
Assignmentsedit
|
|