c简易实现本地数据库

这个数据库一共用到两个头文件

#include"dbtype.h"
#include"XperditDB.h"

dbtype.h提供了一个PList双向链表可以对数据库进行精确的操作

XperditDB.h提供了table一个数据库容器来对数据库进行增删改查

下面是方法介绍：

initTable（table t）

对table变量进行初始化

createTable(PList typeName,char *TabName,table &t)

创建一个新的table，其中typeName为一个Plist，它存放了储存的数据名称，TabName为数据库在本地的名称

getTable(char *tableName,table &t)

获取一个已经存在的table，tableName为已经存在的本地数据库名称

clearTable(table &t)

释放table，但不破坏本地数据库

insert2Table(table &t,PList item)

像table中插入数据，item为插入的数据

delTableElem(table &t,int id)

删除ID=id的那一列数据

getElemInTableFromID(table t,int id)

通过id获取那一列数据

getElemIDInTableFromChar(table t,char *type,char *item)

通过类型名和内容返回该列的id 通常搭配getElemInTableFromID使用

updateDB(table t)

将t同步到本地的数据库

readTable(table t)

在命令行中显示t的所有内容

initList(PList &p)

初始化Plist

PList的基本函数就不写了 详见dbtype.h

下面附上源码：

dbtype.h

#ifndef DBTYPE_H
#define DBTYPE_H
#include<stdio.h>
#include<malloc.h>
#include<string.h>
#define ERROR -1
typedef struct list *PList;
typedef struct Node *PNode;
typedef char *Elem;
struct list{
	int ava;
	PNode head;
	PNode tail;
};
struct Node{
	Elem elem;
	PNode next;
};
int initNode(PNode &p){
	if(!(p=(PNode)malloc(sizeof(Node)))){
		free(p);
		return ERROR;
	}
	p->next=NULL;
	return 1;
}
int initList(PList &p){
	if(!(p=(PList)malloc(sizeof(list)))){
		free(p);
		return ERROR;
	}
	PNode pp;
	initNode(pp);
	p->head=NULL;
	p->tail=NULL;
	p->ava=1;
	return 1;
}
int isEmpty(PList p){
	if(p->ava==1) return 1;
	return 0;
}
void append(PList p,Elem elem){
	PNode pp;
	initNode(pp);
	int len=strlen(elem)+1;
	pp->elem=(Elem)malloc(sizeof(char)*len);
	strcpy(pp->elem,elem);
	if(!(p->head)){
		p->head=pp;
		p->tail=pp;
	}else{
		p->tail->next=pp;
		p->tail=pp;
		
	}
}
int getlen(PList p){
	PNode pp=p->head;
	int re=0;
	while(pp){
		++re;
		pp=pp->next;
	}
	return re;
	
}
void readAllList(PList p){
	if(!isEmpty(p)){
		return;
	}
	PNode pp=p->head;
	while(pp){
		printf("%c",pp->elem);
		pp=pp->next;
	}
	printf("
");
}
Elem getElem(PList p,int id){
	PNode pp=p->head;
	int i=1;
	while(pp){
		if(i==id){
			return pp->elem;
		}
		pp=pp->next;
		i++;
	}
	return 0;
}
void DelElem(PList p,int id){
	PNode pp=p->head;
	int i=1;
	if(id==1){
		p->head=pp->next;
		free(pp);
	}else{
		while(pp){
		if(i+1==id){
			PNode ppp=pp->next;
			pp->next=ppp->next;
			free(ppp->elem);
			free(ppp);
		}
		pp=pp->next;
		i++;
	}
	}
	
}
void insert(PList p,Elem e,int id){
	PNode p2=p->head;
	PNode p3;
	initNode(p3);
	int i=1;
	if(id==1){
		p->head=p3;
		p3->next=p2;
		p3->elem=e;
	}else{
		while(p2){
			if(i+1==id){
				p3->next=p2->next;
				p2->next=p3;
				p3->elem=e;	
			}
			i++;
			p2=p2->next;
		}
	}
}
void clearList(PList p){
	PNode pp=p->head;
	while(pp){
		PNode p3=pp;
		pp=pp->next;
		free(p3->elem);
		free(p3);
	}
	free(p);
}
void listcat(PList p1,PList p2){
	p1->tail->next=p2->head;
	p1->tail=p2->tail;
	free(p2);
}
int getid(PList p,char *ch){
	PNode n=p->head;
	int id=1;
	while(n){
		if(strcmp(n->elem,ch)==0){
			return id;
		}
		id++;
		n=n->next;
	}
	return 0;
}
#endif

XperditDB.h

#ifndef XPERDITDB_H
#define XPERDITDB_H
#include<stdio.h>
#include<string.h>
#include<malloc.h>
#include <stdlib.h>
#include"dbtype.h"
typedef char *pchar;
typedef struct stable *table;
struct stable{
	PList type;
	PList item;
	char *path;
};
char* readFile(char *path){
	FILE *fp;   
    char *ch1;  
    char ch;
    if((fp=fopen(path,"r"))==NULL) {  
        printf("file cannot be opened/n");     
    }   
    int len=0;
    while((ch=fgetc(fp))!=EOF)   
    	len++;
   	ch1=(char*)malloc(sizeof(char)*((int)(len+1)));
   	strcpy(ch1,"");
   	fclose(fp);
   	if((fp=fopen(path,"r"))==NULL) {  
        printf("file cannot be opened/n");     
    }  
   	int i=0;
    while((ch=fgetc(fp))!=EOF)  {
    	*(ch1+i)=ch;
    	i++;
    } 	  
    
    fclose(fp);
    return ch1;
}
void writeFile(char* ch,char* path){
	FILE *fp;
	if((fp=fopen(path,"w"))==NULL) {  
        printf("file cannot be opened/n");     
    }  
    int len=strlen(ch);
    for(int i=0;i<len;i++){
    	fputc(ch[i],fp);
    }
    fclose(fp);
}
char* mix(PList p){
	PNode pp=p->head;
	int len=0;
	while(pp){
		len+=strlen(pp->elem)+1;
		pp=pp->next;
	}
	char *ch=(char*)malloc(sizeof(char)*((len+1)+1));
	strcpy(ch,"");
	pp=p->head;
	while(pp){
		strcat(ch,pp->elem);
		strcat(ch,"/");
		pp=pp->next;
	}
	strcat(ch,"<");
	clearList(p);
	return ch;
	
}
char* mixTAC(PList p1,PList p2){
	char *ch1=mix(p1);
	char *ch2=mix(p2);
	int len=strlen(ch1)+strlen(ch2)+2;
	char *ch=(char*)malloc(sizeof(char)*len);
	strcpy(ch,"");
	strcat(ch,ch1);
	strcat(ch,"*");
	strcat(ch,ch2);
	return ch;
}
char* strsub(char *ch,int start,int end){
	char *cho=(char*)malloc(sizeof(char)*(end-start+2));
	int i=start;
	int j=0;
	while(*(ch+i)){
		*(cho+j)=*(ch+i);
		if(i==end){
			break;
		}
		i++;
		j++;
	}
	*(cho+j+1)=0;
	return cho;
}
void decodePart(char *ch,PList p){
	int i=0;
	while(*(ch+i)!=47) i++;
	append(p,strsub(ch,0,i-1));
	int len=strlen(ch);
	if(*(ch+i+1)==60){
		return;
	}
	decodePart(strsub(ch,i+1,len-1),p);
	
}
void decodeDB(char *ch,PList &p1,PList &p2){
	char *ch1;
	char *ch2;
	int breakp=0;
	int i=0;
	while(*(ch+i)){
		if(*(ch+i)==42){
			break;
		}
		i++;
	}
	ch1=(char*)malloc(sizeof(char)*(i+1));
	ch2=(char*)malloc(sizeof(char)*(strlen(ch)-i));
	ch1=strcpy(ch1,"");
	ch2=strcpy(ch2,"");
	ch1=strsub(ch,0,i-1);
	ch2=strsub(ch,i+1,strlen(ch)-1);	
	decodePart(ch1,p1);
	decodePart(ch2,p2);
}
void readData(PList &p1,PList &p2){
	int len1=getlen(p1);
	int len2=getlen(p2);
	for(int j=1;j<=len2;j++){
		if(j%len1==0){
			printf("%s :",getElem(p1,len1));
		}else{
			printf("%s :",getElem(p1,j%len1));
		}		
		printf("%s
",getElem(p2,j));
	}
	
}
void getdata(char *path,PList &p1,PList &p2){
	char *cho=readFile(path);
	int k=0;
	int kk=0;
	int len=strlen(cho);
	while(kk!=2){
		if(*(cho+k)==60){
			kk++;
		}
		k++;
	}
	char *ch;
	ch=strsub(cho,0,k);
	initList(p1);
	initList(p2);
	decodeDB(ch,p1,p2);
}
void writedata(PList p1,PList p2,char *TabName){
	char *ch=mixTAC(p1,p2);
	writeFile(ch,TabName);
};
void readDB(char *TabName){
	PList p1,p2;
	getdata(TabName,p1,p2);
	readData(p1,p2);
	clearList(p1);
	clearList(p2);
}
void initTable(table &t){
	t=(table)malloc(sizeof(stable));	
}
void createTable(PList typeName,char *TabName,table &t) {
	PList Pobj;
	initList(Pobj);
	int len=getlen(typeName);
	for(int i=0;i<len;i++){
		append(Pobj,"NULL");
	}
	initTable(t);
	t->type=typeName;
	t->item=Pobj;
	t->path=TabName;		
}
void updateDB(table t){
	writedata(t->type,t->item,t->path);
};
void getTable(char *tableName,table &t){
	PList p1,p2;
	initList(p1);
	initList(p2);
	initTable(t);
	getdata(tableName,p1,p2);
	t->type=p1;
	t->item=p2;
	t->path=tableName;
}
void readTable(table t){
	readData(t->type,t->item);
}
void insert2Table(table &t,PList item){
	listcat(t->item,item);
	int i=0;
	for(;i<3;i++){
		if(strcmp(getElem(t->item,1),"NULL")==0){
		DelElem(t->item,1);
	}
	}
	
}
void delTableElem(table &t,int id){
	int lenType=getlen(t->type);
	PList pit=t->item;
	for(int i=0;i<lenType;i++){
		DelElem(pit,(id-1)*lenType+1);
	}
}
void clearTable(table &t){
	clearList(t->type);
	clearList(t->item);
	free(t);
}
PList getElemInTableFromID(table t,int id){
	int len=getlen(t->type);
	PList out;
	initList(out);
	for(int i=1;i<=len;i++){
		append(out,getElem(t->item,len*(id-1)+i));
	}
	return out;
}
int getElemIDInTableFromChar(table t,char *type,char *item){
	int len1=getlen(t->type);
	int id=getid(t->type,type);
	int len2=getlen(t->item);
	int len =len2/len1;
	for(int i=1;i<=len;i++){
		if(strcmp(getElem(t->item,len1*(i-1)+id),item)==0){
			return i;
		}
	}
	return 0;
}
#endif

有需要的话再更新几个demo