C++中重复调用memcpy函数，会导致内存不断增加是怎么回事？

Question

for(int i = 0 ; i < numOfTraces ; i++){        TraceClass *trace = new TraceClass();        qDebug() << trace;        printf("ii=%d,size =%d\n",i,sizeof(TraceClass));        trace->readTraceHead(fmp);        delete trace;        trace = NULL;        fmp += 240 + 4L * samples;        progress->setValue(i+1);        qApp->processEvents(QEventLoop::ExcludeUserInputEvents);        if(progress->wasCanceled()){            inLineHashMap.clear();            xLineHashMap.clear();            return false;        }    }voidTraceClass::readTraceHead(uchar*fmp){char*s;longtemplong;shorttempshort;memcpy(&templong,fmp,4);fmp+=4;s=(char*)&templong;TraceHead.TRACENUMBERLINE=BinToLong(s);//001-004 }（1）如果把fmp +=240 + 4L * samples；注释掉，运行程序，内存不会变化很大；（2）如果把memcpy这句话注释掉，内存不会飙升，如果不注释掉，内存上升很快达到G。             请了解的大神指教