int main(int argc, const char * argv[]) {
    // insert code here...
    
    
    string str3 = "/Users/Ethan/Downloads/aaa/platform-tools/adb shell screencap -p";
    NSMutableData *resultData=[[NSMutableData alloc] init];
    FILE * fstream = NULL;

    if(NULL==(fstream=popen(str3.c_str(),"r")))
    {
        fprintf(stderr,"execute command failed: %s",strerror(errno));
        return NULL;
    }
    
   FILE *png = fopen("/var/folders/_g/mmsygkld2sv2pl719654cscm0000gn/T/2.png", "w");

    char tmp[1024]; //存储每一行输出
    size_t all=0;
    size_t readNum=fread(tmp,1, sizeof(tmp)-1, fstream);

    while (readNum!=0)
    {
       
        if (tmp[readNum-1] == 0xd)
        {
            tmp[readNum++] = fgetc(fstream);
        }
        
      
        for (unsigned int i = 0; i < readNum; ++i) {
            if (tmp[i] == 0xd && tmp[i+1] == 0xa ) {
                tmp[i] = 0xa;
                for (unsigned int j = i+1; j < readNum - 1; ++j)
                    tmp[j] = tmp[j+1];
                readNum--;
            }
        }
         all=all+readNum;
        
        //写到文件
        fwrite(tmp, 1, readNum, png);
        //直接放到内存
        [resultData appendBytes:tmp length:readNum];
       
        readNum=fread(tmp,1, sizeof(tmp)-1, fstream);
    }
 
   
    NSImage *img=[[NSImage alloc] initWithData:resultData];
    
    NSLog(@"%f",img.size.width);

   
  
    return 0;
}