Difference between revisions of "C programming/Structures"
From Teknologisk videncenter
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= Arrays of structures example = | = Arrays of structures example = | ||
<source lang=c> | <source lang=c> | ||
| + | #include <stdio.h> | ||
| + | #include <stdlib.h> | ||
#include <string.h> | #include <string.h> | ||
#define STUDENTS 16 | #define STUDENTS 16 | ||
Revision as of 15:47, 21 November 2010
Basic structrues
Example 1
Create and instantiate a structure
#include <stdio.h>
#include <stdlib.h>
struct coor {
int x;
int y;
};
int main( void ) {
struct coor place;
place.x = 17;
place.y = 19;
printf("Tallet er %i\n",place.x+place.y);
return(0);
}
Example 2
Same as example 1, but using as typedef
#include <stdio.h>
#include <stdlib.h>
struct coor {
int x;
int y;
};
typedef struct coor coordinate;
int main( void ) {
coordinate place;
place.x = 17;
place.y = 19;
printf("Tallet er %i\n",place.x+place.y);
return(0);
}
Example 3
In example 3 the memory is reserver with malloc and indirect addressing is used to access the structure.
#include <stdio.h>
#include <stdlib.h>
struct coor {
int x;
int y;
};
typedef struct coor coordinate;
int main( void ) {
coordinate *place = malloc( sizeof( coordinate ) );
(*place).x = 17; /* One form of indirect addressing shown */
place->y = 19; /* Another form of indirect addressing shown */
printf("Tallet er %i\n",place->x + place->y);
free( place ); /* Always remember to free allocated memory (Good habbit)*/
return( 0 );
}
Arrays of structures example
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define STUDENTS 16
#define FREE 0
struct person {
int id;
char name[25];
char surname[25];
};
typedef struct person p;
int main( void ) {
p class[ STUDENTS ];
/* Initialize p*/
int i;
for ( i = 0; i < STUDENTS ; i++ ) {
class[i].id = FREE; /* 0 = No student allocated */
}
/* Populate class */
class[0].id = 101; strcpy(class[0].name,"Henrik"); strcpy(class[0].surname,"Thomsen");
class[7].id = 145; strcpy(class[7].name,"Anders"); strcpy(class[7].surname,"And");
/* Parse structure and print populated students */
for ( i=0; i < STUDENTS ; i++ ) {
if ( class[i].id != FREE ) {
printf("Student: ID: %i name: %s %s\n",class[i].id, class[i].name, class[i].surname);
fflush(stdout); /* Empty buffer to stdout (Just for fun) */
}
}
}