C语言及程序设计进阶例程-30 联合体及其应用

贺老师教学链接 C语言及程序设计进阶 本课讲解

联合体的概念

#include <stdio.h> union un { int i; short int si[2]; char c[4]; }; int main() { union un x; x.c[0]='A'; x.c[1]='B'; x.c[2]='C'; x.c[3]='D'; printf("%c, %c, %c, %c\n", x.c[0], x.c[1], x.c[2], x.c[3]); printf("%d, %d\n", x.si[0], x.si[1]); printf("%d\n", x.i); return 0; }

应用：IP的表示

#include <stdio.h> union IP { unsigned char part[4]; unsigned int address; }; void copyIp(union IP *a, int n[]) { int i; for(i=0; i<4; i++) a->part[i]=n[i]; return; } int main() { union IP ip1, ip2; int nums[4]= {202,194,116,97}; copyIp(&ip1, nums); printf("ip1: %d.%d.%d.%d\n", ip1.part[0], ip1.part[1], ip1.part[2], ip1.part[3]); printf("ip1: %d\n", ip1.address); ip2.address=234567; printf("ip2: %d.%d.%d.%d\n", ip2.part[0], ip2.part[1], ip2.part[2], ip2.part[3]); printf("ip2: %d\n", ip2.address); if(ip1.address == ip2.address) printf("same ip.\n"); else printf("not same ip.\n"); return 0; } 相关资源：python入门教程(PDF版)