程式碼示例：

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

const int MAXSIZE = 128; // 每個單詞不超過128個字元

typedef struct node {

char word[MAXSIZE];

int size;

struct node *next;

}*List,*pNode;

List Init() {

List head;

head = (pNode)malloc(sizeof(struct node));

head->size = 0;

head->word[0] = "\0";

head->next = NULL;

return head;

}

char *toLower(char s[]) { // 小寫變大寫

int i = 0;

while(s[i]) {

if(s[i] >= "A" && s[i] <= "Z")

s[i] += "a" - "A";

++i;

}

return s;

}

void Add(List head,char s[]) { // 新增到連結串列中

pNode p = head;

char t[MAXSIZE];

strcpy(t,toLower(s));

while(p->next) {

if(strcmp(p->next->word,t) == 0) {

++p->next->size;

return;

}

p = p->next;

}

p->next = (pNode)malloc(sizeof(struct node));

strcpy(p->next->word,t);

p->next->size = 1;

p->next->next = NULL;

}

void Sort(List head) { // 根據bai各個詞的數量排序(大到小)

pNode p,q,qt;

char ct[MAXSIZE];

int it;

for(p = head; p->next; p = p->next) {

qt = p;

for(q = p->next; q->next; q = q->next) {

if(strlen(qt->next->word) < strlen(q->next->word))

qt = q;

}

if(p != qt) {

strcpy(ct,p->next->word);

strcpy(p->next->word,qt->next->word);

strcpy(qt->next->word,ct);

it = qt->next->size;

qt->next->size = p->next->size;

p->next->size = it;

}

}

}

void Show(List head, int n,FILE *fp) { // 顯示前n個

int i;

pNode p = head->next;

for(i = 0; p; ++i) {

fprintf(fp,"%s\n",p->word);

if(i < n) printf("%3d : %s\n",p->size,p->word);

p = p->next;

}

}

int main() {

char word[MAXSIZE];

List head = Init();

FILE *fin = fopen("data.txt","rt");

FILE *fout = fopen("result.dat","wt");

List list = Init();

if(fin == NULL || fout == NULL) {

printf("不能開啟資料檔案。\n");

return 1;

}

while(fscanf(fin,"%s",word) == 1)

Add(head,word);

fclose(fin);

Show(head,3,fout);

fclose(fout);

return 0;

}