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c笔记一

c的一些笔记
1:声明数组 ,一定要初始化memset();
eg:char buf[12][10];
memset(buf,’\0,sizeof(buf)’);
2:声明指针，给了值再用（貌似很简单可我犯错了）
eg: struct qiao * P;
p=(struct qiao *)maloc(sizeof(struct qiao));
p是可以用的。
3;memcpy函数 memcpy(void *desc,void*src,int num);
desc 和src的空间不能重叠，否则会覆盖src的部分值
4:c中的字符串处理;
c的字符串用char数组表示，一定要在数组末尾加个’\0′;

5:字符串和数值的转换

//把buf的数据放到struct gpsData中   
    /*  
          *提取年月日  
         */  
    gpsData->year=(int)(atol(buf[8])%100);   
    gpsData->month=(int)((atol(buf[8])%10000-gpsData->year)/100);   
    gpsData->day=(int)(atol(buf[8])/10000);   
 
 
 
 
    /*  
         *提取时分秒毫秒  
     */  
    gpsData->hour=((int)atof(buf[0]))/10000;   
    gpsData->second=((int)atof(buf[0]))%100;   
    gpsData->minute=(((int)atof(buf[0]))%10000-gpsData->second)/100;   
    gpsData->minisecond= (int)((long)(atof(buf[0])*1000)%1000);   
 
    /*  
    *提取经度和纬度  
    */  
    char  temp[3];   
    char *tempPoint;   
 
    memset(temp,'\0',sizeof(temp));   
 
    memcpy(temp,buf[4],2);   
    temp[3]='\0';   
 
      gpsData->longitude=atoi(temp);   
 
    tempPoint=buf[4];   
    gpsData->m_longitude=atof(tempPoint+2);   
 
 
 
    memcpy(temp,(char *)buf[2],2);   
    temp[3]='\0';   
    gpsData->latitude=atoi(temp);   
    tempPoint=buf[2];   
    gpsData->m_latitude=atof(tempPoint+2);

转自 http://kulinglei.javaeye.com/blog/392389

This entry was posted on 星期六, 一月 2nd, 2010 at 21:21 and is filed under c. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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