linux读取按行读写文本文件

#include <stdio.h>

#include <unistd.h>

#include <fcntl.h>

#include <string.h>

#include <malloc.h>

#include <stdlib.h>

typedef struct item_t {

char *key;

char *value;

}ITEM;

/*

*去除字符串右端空格

*/

char *strtrimr(char *pstr)

{

int i;

i = strlen(pstr) - 1;

while (isspace(pstr[i]) && (i >= 0))

pstr[i--] = '\0';

return pstr;

}

/*

*去除字符串左端空格

*/

char *strtriml(char *pstr)

{

int i = 0,j;

j = strlen(pstr) - 1;

while (isspace(pstr[i]) && (i <= j))

i++;

if (0<i)

strcpy(pstr, &pstr[i]);

return pstr;

}

/*

*去除字符串两端空格

*/

char *strtrim(char *pstr)

{

char *p;

p = strtrimr(pstr);

return strtriml(p);

}

/*

*从配置文件的一行读出key或value,返回item指针

*line--从配置文件读出的一行

*/

int get_item_from_line(char *line, struct
item_t *item)

{

char *p = strtrim(line);

int len = strlen(p);

if(len <= 0){

return 1;//空行

}

else if(p[0]=='#'){

return 2;

}else{

char *p2 = strchr(p, '=');

*p2++ = '\0';

item->key = (char *)malloc(strlen(p) + 1);

item->value = (char *)malloc(strlen(p2) + 1);

strcpy(item->key,p);

strcpy(item->value,p2);

}

return 0;//查询成功

}

int file_to_items(const char *file, struct
item_t *items, int *num)

{

char line[1024];

FILE *fp;

fp = fopen(file,"r");

if(fp == NULL)

return 1;

int i = 0;

while(fgets(line, 1023, fp))

{

char *p = strtrim(line);

int len = strlen(p);

if(len <= 0)

{

continue;

}

else if(p[0]=='#')

{

continue;

}

else

{

char *p2 = strchr(p, '=');

/*这里认为只有key没什么意义*/

if(p2 == NULL)

continue;

*p2++ = '\0';

items[i].key = (char *)malloc(strlen(p) + 1);

items[i].value = (char *)malloc(strlen(p2) + 1);

strcpy(items[i].key,p);

strcpy(items[i].value,p2);

i++;

}

}

(*num) = i;

fclose(fp);

return 0;

}

/*

*读取value

*/

int read_conf_value(const char *key,char *value1,const char *file)

{

char line[1024];

char *key1,*key3,*key2;

FILE *fp;

fp = fopen(file,"r");

if(fp == NULL)

return 1;//文件打开错误

while (fgets(line, 1023, fp)){

ITEM item;

get_item_from_line(line,&item);

if(!strcmp(item.key,key)){

strcpy(value1,item.value);

fclose(fp);

free(item.key);

free(item.value);

break;

}

}

return 0;//成功

}

int write_conf_value(const char *key,char *value,const char *file)

{

ITEM items[20];// 假定配置项最多有20个

int num;//存储从文件读取的有效数目

file_to_items(file, items, &num);

int i=0;

//查找要修改的项

for(i=0;i<num;i++){

if(!strcmp(items[i].key, key)){

items[i].value = value;

break;

}

}

// 更新配置文件,应该有备份，下面的操作会将文件内容清除

FILE *fp;

fp = fopen(file, "w");

if(fp == NULL)

return 1;

i=0;

for(i=0;i<num;i++){

fprintf(fp,"%s=%s\n",items[i].key, items[i].value);

//printf("%s=%s\n",items[i].key, items[i].value);

}

fclose(fp);

//清除工作

/* i=0;

for(i=0;i<num;i++){

free(items[i].key);

free(items[i].value);

}*/

return 0;

}

void main(void)

{

char *key;

char *value=NULL,*value1=NULL;

char *file;

file="/home/wangwei/ww/file/from_file";

key="IP";

value=(char *)malloc(sizeof(char)*30);

value1=(char *)malloc(sizeof(char)*30);

read_conf_value(key,value,file);

printf("IP = %s\n",value);

key="MASK";

read_conf_value(key,value,file);

printf("MASK = %s\n",value);

key="GATEWAY";

read_conf_value(key,value,file);

printf("GATEWAY = %s\n",value);

free(value);

free(value1);

value=NULL;

value1=NULL;

}

FROM: http://blog.chinaunix.net/uid-26921272-id-3328858.html