[C] Singly Linked list(전역변수)

#include <stdio.h> #include <stdlib.h>//! exit #include <time.h>//! time #define MAX 10 typedef struct tnode_ {         int item;         tnode_ *next; }tnode; tnode_ *head,*tail;//! 대가리와 꼬리 void display_node() {         int num=1;//! node number counter         tnode_ *tmp;         tmp=head->next;         printf("\n===================================");         while(tmp!=tail) {                                 printf("\n %d아이템은  %d 입니다",num,tmp->item);                 tmp=tmp->next;                 num++;         }//! end while         printf("\n==================================="); } void find_node() {         int find,num=1,cnt=0;//! find item ,node number,find node counter         tnode_ *tmp;         printf("\n찾을 아이템을 입력하시오 : ");         scanf("%d",&find);         tmp=head->next;//! first node         while(tmp!=tail) {//! node 끝까지 찾음                 if(tmp->item==find) {                         printf("\n 아이템 %d는 %d번째 있다",find,num);                         cnt++;                 }//! end if                 tmp=tmp->next;                 num++;         }//! end while         if(cnt==0) printf("\n찾는 노드가 없다"); } void del_node_all() {         int find;//! find item         tnode_ *tmp_b,*tmp_c;//! before 전노드 current 현재노드         printf("\n삭제할 아이템을 입력하시오(같은 아이템 모두 삭제) : ");         scanf("%d",&find);         tmp_b=head;         tmp_c=head->next;         while(tmp_b!=tail) {//! node 끝까지 찾음 마지막 노드 삭제고려                 if(tmp_c->item==find) {                         tmp_b->next=tmp_c->next;                         free(tmp_c);                         printf("\n아이템 %d 삭제되었습니다",find);                 }//! end if                 tmp_b=tmp_b->next;                 tmp_c=tmp_b->next;         }//! end while } void insert_node_rear() {//! MAX=10 개의 RANDOM NUMBER INSERT rear         tnode_ *tmp,*tmp_e;         tmp_e=head;//! end node         srand((unsigned)time(NULL));         for(int i=0;i<MAX;i++) {                 if((tmp=(tnode_*)malloc(sizeof(tnode_)))==NULL) {                         fprintf(stderr,"Memory is Full");                 }                 while(tmp_e->next!=tail) {//! search end node                         tmp_e=tmp_e->next;                 }//! end while                 tmp->item=rand()%11;                 tmp->next=tail;                 tmp_e->next=tmp;                 //head=tmp_e;         }//! end for         printf("\n입력 완료"); } void insert_node_front() {//! MAX=10 개의 RANDOM NUMBER INSERT front         tnode_ *tmp;         srand((unsigned)time(NULL));         for(int i=0;i<MAX;i++) {                 if((tmp=(tnode_*)malloc(sizeof(tnode_)))==NULL) {                 fprintf(stderr,"Memory is Full");                 }                 tmp->item=rand()%11;                 tmp->next=head->next;                 head->next=tmp;         }//! end for         printf("\n입력 완료"); }          void init_node() {//! head,tail initialize         if((head=(tnode_*)malloc(sizeof(tnode_)))==NULL) {                 fprintf(stderr,"Memory is Full");                 exit(1);         }         if((tail=(tnode_*)malloc(sizeof(tnode_)))==NULL) {                 fprintf(stderr,"Memory is Full");                 exit(1);         }         head->next=tail;         tail->next=tail;//! 무한루프 방지 } int main() {         int cmd;         init_node();         while(1) {                 printf("\n============================================================");                 printf("\n    1)앞에삽입(랜덤 10개씩)      2)뒤에삽입 랜덤 10개씩     ");                 printf("\n    3)삭제          4)검색       5)출력        Other)종료   ");                 printf("\n============================================================");                 printf("\nCommand> ");                 scanf("%d",&cmd);                 switch(cmd) {                 case 1 :                         insert_node_front();                         break;                 case 2 :                         insert_node_rear();                         break;                 case 3 :                         del_node_all();                         break;                 case 4 :                         find_node();                         break;                 case 5 :                         display_node();                         break;                 default :                         exit(0);                 }         }         return 0; }