How to read line by line or a whole text file at once

Question

I m in a tutorial which introduces files  how to read and write from to file   First of all  this is not a homework  this is just general help I m seeking   I know how to read one word at a time  but I don t know how to read one line at a time or how to read the whole text file   What if my file contains 1000 words  It is not practical to read each word   My text file named  Read  contains the following   I love to play games I love reading I have 2 books  This is what I have accomplished so far    include  lt iostream gt   include  lt fstream gt   using namespace std  int main        ifstream inFile    inFile open  Read txt       inFile  gt  gt    Is there any possible way to read the whole file at once  instead of reading each line or each word separate

User · Answer

Well  to do this one can also use the freopen function provided in C   - http   www cplusplus com reference cstdio freopen  and read the file line by line as follows -    include lt cstdio gt   include lt iostream gt   using namespace std   int main       freopen  path to file    rb   stdin      string line     while getline cin  line          cout  lt  lt  line  lt  lt  endl     return 0

User · Answer

you can also use this to read all the lines in the file one by one then print i  include  lt iostream gt   include  lt fstream gt   using namespace std     bool check file is empty   ifstream amp  file       return file peek      EOF      int main           string text 256       int lineno       ifstream file  quot text txt quot        int num   0       while   check file is empty file                     getline file   text num            num              for  int i   0  i  lt  num   i                  cout  lt  lt   quot  nthis is the text in  quot   lt  lt    quot line  quot   lt  lt  i 1  lt  lt   quot      quot   lt  lt  text i   lt  lt  endl                    system  quot pause quot         return 0     hope this could help you

User · Answer

You can use std  getline     include  lt fstream gt   include  lt string gt   int main           std  ifstream file  Read txt        std  string str       while  std  getline file  str                    Process str           Also note that it s better you just construct the file stream with the file names in it s constructor rather than explicitly opening  same goes for closing  just let the destructor do the work    Further documentation about std  string  getline   can be read at CPP Reference   Probably the easiest way to read a whole text file is just to concatenate those retrieved lines   std  ifstream file  Read txt    std  string str  std  string file contents  while  std  getline file  str       file contents    str    file contents push back   n

User · Answer

Another method that has not been mentioned yet is std  vector   std  vector lt std  string gt  line   while file  gt  gt  mystr       line push back mystr       Then you can simply iterate over the vector and modify extract what you need

User · Answer

I know this is a really really old thread but I d like to also point out another way which is actually really simple    This is some sample code    include  lt iostream gt   include  lt fstream gt   include  lt string gt  using namespace std   int main          ifstream file  filename txt        string content       while file  gt  gt  content            cout  lt  lt  content  lt  lt                 return 0

User · Answer

I think you could use istream  read   function  You can just loop with reasonable chunk size and read directly to memory buffer  then append it to some sort of arbitrary memory container  such as std  vector   I could write an example  but I doubt you want a complete solution  please let me know if you shall need any additional information

User · Answer

hello bro this is a way to read the string in the exact line using this code hope this could help you    include  lt iostream gt   include  lt fstream gt   using namespace std    int main           string text 1       int lineno       ifstream file  quot text txt quot        cout  lt  lt   quot tell me which line of the file you want    quot        cin  gt  gt  lineno           for  int i   0  i  lt  lineno   i                           getline file   text 0                   cout  lt  lt   quot  nthis is the text in which line you want befor      quot   lt  lt  text 0   lt  lt  endl       system  quot pause quot         return 0     Good luck

[c++] How to read line by line or a whole text file at once?

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