C-22

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C-22

  1. 1. Lecture 22Lecture 22 Version 1.0Version 1.0 More on FilesMore on Files
  2. 2. 2Rushdi Shams, Dept of CSE, KUET, Bangladesh A File Copy ProgramA File Copy Program  We will take a look at how you read from a fileWe will take a look at how you read from a file  And then how you can put the content of thatAnd then how you can put the content of that file into another filefile into another file
  3. 3. 3Rushdi Shams, Dept of CSE, KUET, Bangladesh
  4. 4. 4Rushdi Shams, Dept of CSE, KUET, Bangladesh File Opening ModesFile Opening Modes  Read (r)Read (r) Searches the fileSearches the file If the search is successfulIf the search is successful load the file into memoryload the file into memory set a pointer at the beginning of the fileset a pointer at the beginning of the file If the file cannot be openedIf the file cannot be opened returns NULLreturns NULL Only reads from fileOnly reads from file
  5. 5. 5Rushdi Shams, Dept of CSE, KUET, Bangladesh File Opening ModesFile Opening Modes  Write (w)Write (w) Searches the fileSearches the file If the file existsIf the file exists it is overwrittenit is overwritten If notIf not a new file is createda new file is created If the file cannot be openedIf the file cannot be opened returns NULLreturns NULL Only writes to fileOnly writes to file
  6. 6. 6Rushdi Shams, Dept of CSE, KUET, Bangladesh File Opening ModesFile Opening Modes  Append (a)Append (a) Searches the fileSearches the file If the search is successfulIf the search is successful load the file into memoryload the file into memory set a pointer at the end of the fileset a pointer at the end of the file If the file cannot be openedIf the file cannot be opened returns NULLreturns NULL Adding new contents in the fileAdding new contents in the file
  7. 7. 7Rushdi Shams, Dept of CSE, KUET, Bangladesh File Opening ModesFile Opening Modes  Append Plus (a+)Append Plus (a+) Searches the fileSearches the file If the search is successfulIf the search is successful load the file into memoryload the file into memory If not foundIf not found create a new filecreate a new file If the file cannot be openedIf the file cannot be opened returns NULLreturns NULL Reading, appending in fileReading, appending in file Cannot modifyCannot modify
  8. 8. 8Rushdi Shams, Dept of CSE, KUET, Bangladesh File Opening ModesFile Opening Modes  Read Plus (r+)Read Plus (r+) Searches the fileSearches the file If the search is successfulIf the search is successful load the file into memoryload the file into memory set a pointer at first characterset a pointer at first character If the file cannot be openedIf the file cannot be opened returns NULLreturns NULL Reading, writing, modifying contents in the fileReading, writing, modifying contents in the file
  9. 9. 9Rushdi Shams, Dept of CSE, KUET, Bangladesh File Opening ModesFile Opening Modes  Write Plus (w+)Write Plus (w+) Searches the fileSearches the file If the file existsIf the file exists it is overwrittenit is overwritten If notIf not a new file is createda new file is created If the file cannot be openedIf the file cannot be opened returns NULLreturns NULL Writing, reading and modifying contentsWriting, reading and modifying contents
  10. 10. 10Rushdi Shams, Dept of CSE, KUET, Bangladesh String in FilesString in Files  So far we have seen how to manipulateSo far we have seen how to manipulate characters in filescharacters in files  Now, we will see that handling strings in files isNow, we will see that handling strings in files is as easy as handling charactersas easy as handling characters  At first we will see how to write strings into aAt first we will see how to write strings into a filefile
  11. 11. 11Rushdi Shams, Dept of CSE, KUET, Bangladesh
  12. 12. 12Rushdi Shams, Dept of CSE, KUET, Bangladesh  Now we will see how to read strings from filesNow we will see how to read strings from files
  13. 13. 13Rushdi Shams, Dept of CSE, KUET, Bangladesh

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