Stream from file with <fstream>

Question

How it's possible to read characters from file without loosing the spaces?
I have a file which contains for istance this:
The quick brown fox jumps over the lazy dog.
When I read from file (a character a time), I lose the spaces, but the all other characters are correctly read. Why?
This is an example of code:

unsigned int cap = (unsigned)strlen("The quick brown fox jumps over the lazy dog."); char c[cap]; int i = 0; while (!fIn.eof()) { fIn >> c[i]; ++i; } for (int i = 0; i < cap; i++) cout << c[i];

When i print the array, all spaces are missing. Could you tell me how I can avoid this problem?

jrok · Accepted Answer · 2012-01-09 12:57:03Z

You can use the stream manipulators declared in <iomanip>.

std::noskipws is the one you want, which instructs stream extraction operators not to skip whitespaces.

#include <iostream> #include <iomanip> #include <fstream> #include <algorithm> int main() { std::ifstream ifs("x.txt"); ifs >> std::noskipws; std::copy(std::istream_iterator<char>(ifs), std::istream_iterator<char>(), std::ostream_iterator<char>(std::cout)); }

The other option is to use raw input functions fstream::get(), fstream::read().

I assume this is because the istream::operator>>() was designed to be a console input method? (similar to how arguments to a program are tokenized by spaces). As opposed to other read/getline functions available in istream that act more like a file reader?

Ivaylo Strandjev · Accepted Answer · 2012-01-09 12:52:17Z

2

Use the method "get":

ifstream in("try.in"); char c; while((c = in.get()) && in) { cout << c; }

answered Jan 9, 2012 at 12:52

Ivaylo Strandjev

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6 Comments

Overflowh Over a year ago

In which header get() is defined?

Ivaylo Strandjev Over a year ago

For this use you need both fstream and iostream.

Omar K Over a year ago

how does (c = in.get()) actually set c equal to the next character. From what I understand putting that in the while loop just checks to see if there is another character. Can you explain that please?

Ivaylo Strandjev Over a year ago

This is off topic for the question. Try to read the information available online and if there still is something unclear post a separate question

diox8tony Over a year ago

istream::get() returns a char and increments to the next char; cplusplus.com/reference/istream/istream/get istream::peek() also returns a char, but does not increment; maybe you were thinking of that?

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Matthew Walton · Accepted Answer · 2012-01-09 12:52:32Z

By default an istream has the skipws (skip whitespace) flag set. This skips leading whitespace when reading.

You can turn it off using std::noskipws from <iomanip>

fIn << std::noskipws; while (!fIn.eof()) { // etc. }

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