How to create a struct on the stack in C?
an answer to 17.4 Extra Credit (in Zed's book "Learn C the Hard Way") using functions
#include <stdio.h>
struct Person {
char *name;
int age;
int height;
int weight;
};
struct Person Person_create(char *name, int age, int height, int weight)
{
struct Person who;
who.name = name;
who.age = age;
who.height = height;
who.weight = weight;
return who;
}
void Person_print(struct Person who)
{
printf("Name: %s\n", who.name);
printf("\tAge: %d\n", who.age);
printf("\tHeight: %d\n", who.height);
printf("\tWeight: %d\n", who.weight);
}
int main(int argc, char *argv[])
{
// make two people structures
struct Person joe = Person_create("Joe Alex", 32, 64, 140);
struct Person frank = Person_create("Frank Blank", 20, 72, 180);
//print them out and where they are in memory
printf("Joe is at memory location %p:\n", &joe);
Person_print(joe);
printf("Frank is at memory location %p:\n", &frank);
Person_print(frank);
// make everyone age 20 and print them again
joe.age += 20;
joe.height -= 2;
joe.weight += 40;
Person_print(joe);
frank.age += 20;
frank.weight += 20;
Person_print(frank);
return 0;
}
The same way you declare any variable on the stack:
struct my_struct {...};
int main(int argc, char **argv)
{
struct my_struct my_variable; // Declare struct on stack
.
.
.
}
To declare a struct on the stack simply declare it as a normal / non-pointer value
typedef struct {
int field1;
int field2;
} C;
void foo() {
C local;
local.field1 = 42;
}