????????? (????????) http://programming.xjtu.edu.cn

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?????????(????????)http//programming.xjtu.edu.c
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?14? ?????????

• 14.1 ?????
• 14.2 ?
• 14.3 ?????
• 14.4 ???I/O
• 14.5 ????
• 14.6 ?????/??

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14.1 ?????

• ???????
• ?C??????????
• ????????,??????????????

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???????

• 1??????
• ?C???????
• C???????????????????????????????????????????????
• 2?????
• ??C?I/O??????????????????????STL???

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????????

• 1?????????
• 2?C??????
• ??C?????????,??.h??
• ??C????????,??.h??
• ???C?????????????C????,?????C??????????.h?????c?
  ??

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14.2 ?

• 1??C?,??????????
• ???????????????????,????????
• ??????????????????,?????????????????????
• ?????????????
• ????????????
• ????????????????????????????
• 2???
• C????????????????????,????????,?????????????????
  ??????????,??????????????????

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??/???????????
iostream????????
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14.3 ?????

• ???iostream???4???
• cin?????
• cout ?????
• cerr ????????
• clog ????????
• ???I/O ?????iomanip
• ?????? ?????fstream

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??????????

• ????(???)
• 1. ?????????(ltlt)
• 2. ??????put( )??????
• 3. ??????write( )???????

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• ????(???)
• 1. ?????????(gtgt)?
• 2. ??????get( )??????
• 3. ??????getline( )??????
• 4. ??????read( )???????

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??????????

• get()????????
• getline()????????????
• put()??????
• ignore()?????????
• putback()
• peek() ????????????,???????????
• read()/write()????????
• gcount()??????

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?14-1 ??cin?cin.get???

• include ltiostreamgt
• using namespace std
• int main()
• const int SIZE 80
• char ch1,ch2,ch3,buffer1SIZE,buffer2SIZE
• cout ltlt "Enter a sentence\n"
• cin gtgt buffer1
• cout ltlt "The string read with cin is\n" ltlt
  buffer1
• ch1 cin.get()
• ch2 cin.get()

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• cout ltlt "\nThe result of cin.get() is\n" ltlt ch1
  ltlt ch2
• cin.get(ch3)
• cout ltlt "\nThe result of cin.get(ch3) is\n" ltlt
  ch3
• cin.get(buffer2,SIZE)
• cout ltlt "\nThe string read with
  cin.get(buffer2,SIZE) is\n" ltlt buffer2 ltlt endl
• return 0

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14.4 ???I/O

• 1. ??????????????????
• (1) ?????????
• ????????(????)
• basefield? delocthex
• adjustfield? leftrightinternal
• floatfield? seientificfixed

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• (2) ??????????
• long flags( )????????????
• ?cout.flags(iosscientificiosshowpos)
• long setf()???????
• ?cout.setf(iosuppercaseiosscientific)
• long unsetf(long)???????

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• (3) ???????????
• ????int width( )
• ????int fill( )
• ????int precision( )

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??

• include ltiostreamgt
• using namespace std
• int main()
• cout.precision (4)
• cout.width(10)
• coutltlt10.12345ltltendl
• cout.fill ('')
• cout.width (10)
• coutltlt10.12345ltltendl
• coutltlt"Hi"ltltendl
• cout.width (10)
• cout.setf(iosleft)
• coutltlt10.12345ltltendl
• return 0

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?. ????

• ??I/O??????????????iomanip.h????
• ??? ? ?
• skipws ????????
• left ??????????????
• right ??????????????
• internal ?????????????????
• dec ??????????
• oct ??????????
• hex ???????????
• showbase ?????????????
• showpoint ??????????????????0

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• ??? ? ?
• uppercase ????????????AF,????
• ????????E
• showpos ?????????
• fixed ???????????
• scientific ????????????
• untibuf ??????, ostream?osfx???
• ?????????????cerr
• setbase(base) ??????base

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?14-2 ????????

• include ltiostreamgt
• include ltiomanipgt
• using namespace std
• int main()
• int n
• cout ltlt "Enter a decimal number "
• cin gtgt n
• cout ltlt n ltlt " in hexadecimal is " ltlt hex ltlt n
  ltlt '\n'
• ltlt dec ltlt n ltlt " in octal is " ltlt oct ltlt n ltlt
  '\n'
• ltlt setbase( 10 ) ltlt n ltlt " in decimal is " ltlt
  n ltlt endl
• return 0

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?14-3 ???????

• include ltiostreamgt
• include ltiomanipgt
• include ltcmathgt
• using namespace std
• int main()
• double root2 sqrt( 2.0 )
• int places
• cout ltlt setiosflags( iosfixed)
• ltlt "Precision set by the precision member
  function" ltlt endl

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• for ( places 0 places lt 4 places )
• cout.precision( places )
• cout ltlt root2 ltlt '\n'
• cout ltlt "Precision set by the " ltlt "setprecision
  manipulator\n"
• for ( places 0 places lt 4 places )
• cout ltlt setprecision( places ) ltlt root2 ltlt
  '\n'
• return 0

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14.5 ????

• ????
• ???????
• ?
• ?
• ????
• ???

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??????
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?. ???????

• (1) ?????????
• ???
• fstream lt????gt
• ????.open("????,??)
• ??
• fstream ????.open("???",??)

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• ???
• ? ?????
• ofstream lt????gt
• lt????gt.open(?lt???gt?)
• ??
• ofstreamlt????gt.open(?lt???gt?)

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• ? ?????
• ifstreamlt????gt
• lt????gt.open(?lt???gt?)
• ??
• ifstream lt????gt.open(?lt???gt?)

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• (2) ??????
• ????.close( )

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???? ??
ios?in ?????????,????????????????
ios?out ?????????,??????
ios?ate ????????????????????
ios?app ????????????????
ios?nocreate ???????,???????
ios?noreplace ?????ios ? ate?ios?app,????????,??????
ios?binary ????????????,???????
ios?trunc ?????,???????????????
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?. ?????

• ??????grade?????,???3??????????
• include ltiostreamgt
• include ltfstreamgt
• using namespace std

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• int main()
• ofstream out("grade")
• if(!out)
• cout ltlt "Cannot open the grade file." ltlt endl
• return 1
• out ltlt "C" ltlt " " ltlt89.5 ltlt endl
• out ltlt "English" ltlt " " ltlt 93.5 ltlt endl
• out ltlt "Maths" ltlt " " ltlt 87 ltlt endl
• out.close()
• return 0

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?14-5 ???

• ???14-4???grade??,?????????????
• int main()
• ifstream in("grade")
• if(!in)
• cout ltlt "Cannot open grade file.\n"
• return 1

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• char course20 float grade
• in gtgt course gtgt grade
• cout ltlt course ltlt " " ltlt grade ltlt "\n"
• in gtgt course gtgt grade
• cout ltlt course ltlt " " ltlt grade ltlt "\n"
• in gtgt course gtgt grade
• cout ltlt course ltlt " " ltlt grade ltlt "\n"
• in.close()
• return 0

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?. ?????

• ???????????a?????data.dat?????a?20???,?len???
• ? ??ofstream???????????????????
• ofstream wf(?data.dat?,ios?binary)
• wf.write((char )a, len)

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• ? ??ofstream???????,????open????????
• ofstream wf
• wf.open(?data.dat?,ios?binary)
• wf.write((char )a, sizeof a)

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• ? ???????,???setmode????????
• ofstream wf(?data.dat?)
• wf.setmode(filebuf?binary)
• wf.write((char )a, len)

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• ? ??????????setmode????
• ofstream wf(?data.dat?)
• wfltltbinary
• wf.write((char )a, len)

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?14-6 ????

• include ltiostreamgt
• include ltfstreamgt
• using namespace std
• int main(int argc, char argv)
• char ch
• if(argc!2)
• cout ltlt "Usage ProgramName ltfilenamegt\n"
• return 1
• ifstream in(argv1, iosin iosbinary)

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• if(!in)
• cout ltlt "Cannot open the file."
• return 1
• while(in) // in will be false when eof is
  reached
• in.get(ch)
• if(in) cout ltlt ch
• return 0

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? 14-7 ??????????

• ?3??????????????????????,???????,???????????
• include ltiostreamgt
• include ltfstreamgt
• using namespace std
• struct list
• char course10
• int score

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• int main()
• list st13, st23
• int i
• ofstream out("grade", iosbinary)
• if(!out)
• cout ltlt "Cannot open the grade file.\n"
• return 1

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• for (i0 ilt3 i)
• cin gtgt st1i.course gtgt st1i.score
• out.write((char )st1i, sizeof(st1i))
• out.close()
• ifstream in("grade", iosbinary)
• if(!in)
• cout ltlt "Cannot open the grade file.\n"
• return 1

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• cout ltlt "File grade" ltlt endl
• for (i0 ilt3 i)
• in.read((char )st2i, sizeof(st2i))
• cout ltlt st2i.course ltlt " " ltlt st2i.score
  ltlt endl
• in.close()
• return 0

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????????

• ?????????I/O????????????????????????

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(1) ??????????

• istream istream ?seekg(????)
• istream istream ?seekg(???,????)
• long istream ?tellg( )
• ??,lt????gt?lt???gt??long??,???????lt????gt?????
• cur1?????????
• beg0?????????
• end2?????????

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(2) ??????????

• ostream ostream ?seekp(????)
• ostream ostream ?seekp(???,????)
• long ostream ?tellp( )

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? 14-8 ?????????

• ???????????????????,???????????????,?????????????
  ???????
• include ltiostreamgt
• include ltfstreamgt
• include ltiomanipgt
• include ltcstdlibgt
• using namespace std
• struct TVChannel
• int channelNum
• char channelName20
• void outputLine( ostream output, const TVChannel
  c )

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• int main()
• ofstream outTV( "tv.dat", iosate
  iosbinary)
• if ( !outTV )
• cerr ltlt "File could not be opened." ltlt endl
• return 1
• cout ltlt "Enter channel number " ltlt "(1 to 100, 0
  to end input)\n? "
• TVChannel tv
• cin gtgt tv.channelNum

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• while ( tv.channelNum gt 0 tv.channelNum lt
  100 )
• cout ltlt "Enter Channel Name\n? "
• cin gtgt tv.channelName
• outTV.seekp( ( tv.channelNum - 1 ) sizeof(
  TVChannel ) )
• outTV.write( (char )( tv ), sizeof( TVChannel
  ) )
• cout ltlt "Enter channel number\n? "
• cin gtgt tv.channelNum

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• outTV.close()
• ifstream inTV( "tv.dat", iosin )
• if ( !inTV )
• cerr ltlt "File could not be opened." ltlt endl
• return 1

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• cout ltlt setiosflags( iosleft ) ltlt setw( 10 )
  ltlt "ChannelNum"
• ltlt setw( 20 ) ltlt "Channel Name" ltlt endl
• inTV.read( (char )( tv ), sizeof( TVChannel )
  )
• while ( inTV !inTV.eof() )
• if ( tv.channelNum ! 0 )
• outputLine( cout, tv )
• inTV.read( (char )( tv ), sizeof( TVChannel )
  )
• return 0

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• void outputLine( ostream output, const TVChannel
  tv )
• output ltlt setiosflags( iosleft ) ltlt setw( 10
  )
• ltlt tv.channelNum ltlt setw( 20 ) ltlt
  tv.channelName ltlt '\n'

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??????

• ???12??????Date?,??ltlt???,??Date???
• class Date
• friend ostream operatorltlt( ostream , const
  Date )
• int day, month, year
• ?Date.cpp?????????
• ostream operatorltlt( ostream output, const Date
  d )
• static char monthName 12 "January",
  "February", "March", "April", "May",
• "June", "July", "August", "September",
  "October", "November", "December"
• output ltlt monthName d.month-1 ltlt ' ' ltlt d.day
  ltlt ", " ltlt d.year
• return output

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// Example14-9.cpp????????

• include ltiostream gt
• include "date.h"
• using namespace std
• int main()
• Date today, Olympicday(2004,8,13)
• cout ltlt "Today (the computer's day) is " ltlt
  todayltlt endl
• today 365
• cout ltlt "After 365 days, the date is " ltlt today
  ltlt endl
• Date testday(2,28)

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• cout ltlt "the test date is " ltlt testday ltlt endl
• Date nextday testday 1
• cout ltlt "the next date is " ltlt testday ltlt endl
• today.SystemDate()
• cout ltlt "the Athens Olympic Games openday is "
  ltlt Olympicday ltlt endl
• cout ltlt "And after " ltlt Olympicday-today
• ltlt " days, the Athens Olympic Games will open."
  ltltendl
• return 0

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?14-10 ????????

• // Example 14-10???????
• include ltiostreamgt
• namespace university
• int grade4
• namespace highschool
• int grade3

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• int main()
• stdcoutltlt"The university's grade is
  "ltltuniversitygrade ltltstdendl
• stdcoutltlt"The highschool's grade is
  "ltlthighschoolgrade ltltstdendl
• return 0

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?14-11 ???14-6???

• ???????????ASCII????????????
• include ltiostreamgt
• include ltfstreamgt
• include ltcctypegt
• include ltiomanipgt
• using namespace std
• int main(int argc, char argv)
• if(argc!2)
• cout ltlt "Usage ProgramName ltfilenamegt\n"
• return 1

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• ifstream in(argv1, iosin iosbinary)
• if(!in)
• cout ltlt "Cannot open input file.\n"
• return 1

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• int i, j
• int count 0
• char c16
• cout.setf(iosuppercase)
• while(!in.eof())
• for(i0 ilt16 !in.eof() i) in.get(ci)
• if(ilt16) i-- // get rid of eof
• for(j0 jlti j) cout ltlt ' ' ltlt setw(2) ltlt
  setfill('0') ltlt hex ltlt (int) cj
• for( jlt16 j) cout ltlt " "
• cout ltlt "\t"

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• for(j0 jlti j)
• if(isprint(cj)) cout ltlt cj
• else cout ltlt "."
• cout ltlt endl
• count

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• if(count16)
• count 0
• cout ltlt "Press ENTER to continue "
• cin.get()
• cout ltlt endl
• in.close()
• return 0

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? ? ?

• ???????????
• ???????????????????

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