简单配置文件的读取以及保存。

#define LINE_BUF_SIZE 128
char read_upgrade_version(char *file_path,const char *type, char *value)
{
    char line[LINE_BUF_SIZE] = {0};
    FILE *fp = NULL;
    char *pType = NULL;

    fp = fopen(file_path, "r");
    if (!fp) {
        printf("Can't open %s",file_path);
        return -1;
    }
    while (!feof(fp)) {
        if(fgets(line, LINE_BUF_SIZE, fp) == NULL) {  
            break;  
        }
        pType = strstr(line, "=");
        if(pType == NULL) {
            continue;
        }
        pType = strstr(line, type);
        if (pType) {
            pType ++;
            pType += strlen(type);
            if (pType) {
                strcpy(value, pType);
                break;
            }
        }
    }

    fclose(fp);
    return 0;
    
}

#define LINE_NUM 12
int save_upgrade_version(char *file_path,const char *type, char *value)
{
    int i;
    char flag = 0,cnt = 0;
    struct info_t info[LINE_NUM];
    char linebuffer[LINE_BUF_SIZE] = {0};
    char buffer[LINE_BUF_SIZE * 2];
    char *pType = NULL;
    FILE *fp = fopen(file_path, "r");
    if(fp == NULL)
    {
        printf("open error");
        return 1;
    }
    for(i = 0 ; i < LINE_NUM ; i++)
    {
        char *ret = fgets(linebuffer, sizeof(linebuffer), fp);
        if(ret == NULL)
        {
            break;
        }
        pType = strstr(linebuffer, "=");
        if(pType == NULL) {
            continue;
        }
        memcpy(info[i].type, linebuffer, pType - linebuffer);
        info[i].type[pType - linebuffer] ='';
        strcpy(info[i].value, pType + 1);
        
        if(!strcmp(info[i].type, type))
        {
            strcpy(info[i].value,value);
            info[i].value[strlen(value)] = '
';
            info[i].value[strlen(value) + 1] = '';
            flag = 1;
        }
        memset(linebuffer,0,sizeof(linebuffer));
        cnt++;
    }
    fclose(fp);
    
    fp = fopen(file_path,"w");
    if(fp == NULL)
    {
        return 1;
    }
    if(flag == 0) {
        strcpy(info[cnt].type,type);
        strcpy(info[cnt].value,value);
        info[i].value[strlen(value)] = '
';
        info[i].value[strlen(value) + 1] = '';
        cnt++;
    }
    for(i = 0 ; i < cnt ; i++)
    {
        memset(buffer,0,sizeof(buffer));
        sprintf(buffer,"%s=%s",info[i].type,info[i].value);
        fprintf(fp,"%s",buffer);
    }

    fclose(fp);
    return 0;
}

目前配置文件内容使用“=”号分割。保存时采用的是读取整个文件内容，修改对应行后再保存，可以保存没有存在的字段。如果有很多行的话这个就不适用了。

这个代码只适用与小量的配置保存与更改需要。