struct and union example

1. StructHandler.c:

/*
* StructHandler.c
*
* Created on: Jul 6, 2013
* Author: wangle
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void modifyName(struct student *p);

int main(){
struct student{
char name[50];
char dep[50];
long no;
float score[4];
};

typedef struct student stu_t;

struct student stu[50]={
"wangle", "Math", 80,80,90.5,99,100,
"xuyehui", "biological", 90,90,90,70,100,
"mengmeng", "Math", 100,100,100,100,90
};
int i;
for(i=0; i<3; i++){
printf("%s, %s, %ld, %.2f,%.2f,%.2f,%.2f\n", stu[i].name, stu[i].dep, stu[i].no,
stu[i].score[0], stu[i].score[1], stu[i].score[2], stu[i].score[3]);
}

stu_t * p = stu;
puts((*(p+1)).name); //(1) a pointer call style.
puts((p+1)->name); //(2) common pointer call style. (1) and (2) is the same.

printf("%s\n", (p+2)->name);
printf("%s\n", (*(p+2)).name);
printf("no = %ld\n", p->no);
void modifyName(struct student * p){
p->no = 123456;
}

modifyName(p);
printf("%s\n", (p)->name);
printf("no = %ld\n", p->no);
}

2. UnionHandler.c

/*
* UnionHandler.c
*
* Created on: Jul 6, 2013
* Author: wangle
*/

#include <stdio.h>
int main(){
union unidate{
char c;
int i;
long l;
float f
};
union unidate x;
x.c=65;
printf("c=%c\n", x.c);
x.i = 10;
printf("i=%d\n",x.i);
x.l = 100;
printf("l=%ld\n", x.l);
x.f = 90.5;
printf("f=%.1f\n", x.f);
printf("c=%c\n", x.c);
}