How to Read from a Text File Character by Character in C

Question

I was wondering if someone could help me figure out how to read from a text file in C    character by character  That way  I could have a while loop  while there s still text left  where I store the next character in the text document in a temp variable so I could do something with it  then repeat the process with the next character  I know how to open the file and everything  but temp   textFile getchar   doesn t seem to work  Thanks in advance

User · Answer

To quote Bjarne Stroustrup  The    operator is intended for formatted input  that is  reading objects of an expected type and format  Where this is not desirable and we want to read charactes as characters and then examine them  we use the get   functions    char c  while  input get c            do something with c

User · Answer

Variables     char END OF FILE            char singleCharacter         Get a character from the input file     inFile get singleCharacter          Read the file until it reaches         When read pointer reads the   it will exit loop       This requires that you have a   sign as last character in your text file      while  singleCharacter    END OF FILE                 cout  lt  lt  singleCharacter           inFile get singleCharacter               If you need to store each character  declare a variable and store it      in the while loop

User · Answer

You could try something like   char ch  fstream fin  file   fstream  in   while  fin  gt  gt  noskipws  gt  gt  ch        cout  lt  lt  ch     Or whatever

User · Answer

cnicutar and  Pete Becker have already pointed out the possibility of using noskipws unsetting skipws to read a character at a time without skipping over white space characters in the input   Another possibility would be to use an istreambuf iterator to read the data  Along with this  I d generally use a standard algorithm like std  transform to do the reading and processing   Just for example  let s assume we wanted to do a Caesar-like cipher  copying from standard input to standard output  but adding 3 to every upper-case character  so A would become D  B could become E  etc   and at the end  it would wrap around so XYZ converted to ABC   If we were going to do that in C  we d typically use a loop something like this   int ch  while  EOF     ch   getchar           if  isupper ch            ch     ch -  A    3    26    A       putchar ch       To do the same thing in C    I d probably write the code more like this   std  transform std  istreambuf iterator lt char gt  std  cin                  std  istreambuf iterator lt char gt                    std  ostreambuf iterator lt char gt  std  cout                     int ch    return isupper ch      ch -  A     3    26    A    ch       Doing the job this way  you receive the consecutive characters as the values of the parameter passed to  in this case  the lambda function  though you could use an explicit functor instead of a lambda if you preferred

User · Answer

Re  textFile getch    did you make that up  or do you have a reference that says it should work  If it s the latter  get rid of it  If it s the former  don t do that  Get a good reference   char ch  textFile unsetf ios base  skipws   textFile  gt  gt  ch

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Assuming that temp is a char  and textFile is a std  fstream derivative     The syntax you re looking for is  textFile get  temp

User · Answer

Here is a c   stylish function your can use to read files char by char   void readCharFile string  amp filePath        ifstream in filePath       char c       if in is open              while in good                  in get c                  Play with the data                      if  in eof    amp  amp  in fail            cout  lt  lt   error reading    lt  lt  filePath  lt  lt  endl       in close

User · Answer

There is no reason not to use C  lt stdio h gt  in C    and in fact it is often the optimal choice    include  lt stdio h gt   int main        void  not necessary in C         int c      while   c   getchar       EOF               do something with  c  here           return 0     technically not necessary in C   but still good style

[c++] How to Read from a Text File, Character by Character in C++

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