linux读取按行读写文本文件

1.#include <stdio.h>



2.#include <unistd.h>



3.#include <fcntl.h>



4.#include <string.h>



5.#include <malloc.h>



6.#include <stdlib.h> 



7.



8.



9.typedef struct item_t {



10.    char *key;



11.    char *value;



12.}ITEM;



13.



14./*



15. *去除字符串右端空格



16. */



17.char *strtrimr(char *pstr)



18.{



19.    int i;



20.    i = strlen(pstr) - 1;



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



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



23.    return pstr;



24.}



25./*



26. *去除字符串左端空格



27. */



28.char *strtriml(char *pstr)



29.{



30.    int i = 0,j;



31.    j = strlen(pstr) - 1;



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



33.        i++;



34.    if (0<i)



35.        strcpy(pstr, &pstr[i]);



36.    return pstr;



37.}



38./*



39. *去除字符串两端空格



40. */



41.char *strtrim(char *pstr)



42.{



43.    char *p;



44.    p = strtrimr(pstr);



45.    return strtriml(p);



46.}



47.



48.



49./*



50. *从配置文件的一行读出key或value,返回item指针



51. *line--从配置文件读出的一行



52. */



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



54.{



55.    char *p = strtrim(line);



56.    int len = strlen(p);



57.    if(len <= 0){



58.        return 1;//空行



59.    }



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



61.        return 2;



62.    }else{



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



64.        *p2++ = '\0';



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



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



67.        strcpy(item->key,p);



68.        strcpy(item->value,p2);



69.



70.        }



71.    return 0;//查询成功



72.}



73.



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



75.{



76.    char line[1024];



77.    FILE *fp;



78.    fp = fopen(file,"r");



79.    if(fp == NULL)



80.        return 1;



81.    int i = 0;



82.    while(fgets(line, 1023, fp))



83.    {



84.        char *p = strtrim(line);



85.        int len = strlen(p);



86.        if(len <= 0)



87.        {



88.            continue;



89.        }



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



91.        {



92.            continue;



93.        }



94.        else



95.        {



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



97.            /*这里认为只有key没什么意义*/



98.            if(p2 == NULL)



99.                continue;



100.            *p2++ = '\0';



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



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



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



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



105.



106.            i++;



107.        }



108.    }



109.    (*num) = i;



110.    fclose(fp);



111.    return 0;



112.}



113.



114./*



115. *读取value



116. */



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



118.{



119.    char line[1024];



120.    char *key1,*key3,*key2;



121.    FILE *fp;



122.    fp = fopen(file,"r");



123.    if(fp == NULL)



124.        return 1;//文件打开错误



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



126.        ITEM item;



127.        get_item_from_line(line,&item);



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



129.



130.            strcpy(value1,item.value);



131.            fclose(fp);



132.            free(item.key);



133.            free(item.value);



134.            break;



135.        }



136.    }



137.    return 0;//成功



138.



139.}



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



141.{



142.    ITEM items[20];// 假定配置项最多有20个



143.    int num;//存储从文件读取的有效数目



144.    file_to_items(file, items, &num);



145.



146.    int i=0;



147.    //查找要修改的项



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



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



150.            items[i].value = value;



151.            break;



152.        }



153.    }



154.



155.    // 更新配置文件,应该有备份，下面的操作会将文件内容清除



156.    FILE *fp;



157.    fp = fopen(file, "w");



158.    if(fp == NULL)



159.        return 1;



160.



161.    i=0;



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



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



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



165.    }



166.    fclose(fp);



167.    //清除工作



168. /*i=0;



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



170.        free(items[i].key);



171.        free(items[i].value);



172.    }*/



173.



174.    return 0;



175.



176.}



177.



178.void main(void)



179.{



180.    char *key;



181.    char *value=NULL,*value1=NULL;



182.    char *file;



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



184.



185.    key="IP";



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



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



188.    read_conf_value(key,value,file);



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



190.



191.    key="MASK";



192.    read_conf_value(key,value,file);



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



194.



195.    key="GATEWAY";



196.    read_conf_value(key,value,file);



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



198.    free(value);



199.    free(value1);



200.    value=NULL;



201.    value1=NULL;



202.}