reversing a file

[neo]

Hello everyone,
I want to write a function that takes a simple text file as input and
outputs a file such that the last line in the input file becomes the first
line in the output file and the first line of the input becomes the last
line of output.

I had written this function as:

void fileReverse(char* inputFileName, char *outputFileName)
{
FILE *input = fopen(inputFileName, "r");
FILE *output = fopen(outputFileName, "w");

int ch, prev = '\n';
while ( (ch = fgetc(input)) != EOF ) /* Read all chars in the file. */
{
if ( ch == '\n' )
{
fputc(EOF, output);
fseek(output, 0, SEEK_SET);
// rewind(output);
fputc(ch, output);
fseek(output, 0, SEEK_SET);
// rewind(output);
}
else
{
fputc(ch, output);
}
prev = ch; /* Keep a copy to later test whether... */
}

if ( prev != '\n' ) /* ...the last line did not end in a newline. */
{
fputc('\n', output);
}

fclose(output);
fclose(input);
}

But on giving input file input.txt as:
line 1
line 2
line 3

it gives output file output.txt as:
line 3

Can someone suggest me a solution?

Regards,
neo.

 

[TB]

neo skrev:

Hello everyone,
I want to write a function that takes a simple text file as input and
outputs a file such that the last line in the input file becomes the first
line in the output file and the first line of the input becomes the last
line of output.

I had written this function as:

But on giving input file input.txt as:
line 1
line 2
line 3

it gives output file output.txt as:
line 3

Can someone suggest me a solution?

#include <fstream>
#include <string>
#include <vector>
#include <algorithms>

int main(int argc, char* argv[])
{
std::ifstream in("in.txt");
if(in) {
std::vector<std::string> v;
while(!in.eof() && in) {
std::string str;
std::getline(in,str,'\n');
v.push_back(str);
}
std:fstream out("out.txt");
if(out) {
std::copy(v.rbegin(),v.rend(),
std:stream_iterator<std::string>(out,"\n"));
}
}
return 0;
}

 

[Sumit Rajan]

#include <fstream>
#include <string>
#include <vector>
#include <algorithms>

#include <algorithm>

 

[Vikram]

neo skrev:

Hello everyone,
I want to write a function that takes a simple text file as input and
outputs a file such that the last line in the input file becomes the first
line in the output file and the first line of the input becomes the last
line of output.

I had written this function as:

But on giving input file input.txt as:
line 1
line 2
line 3

it gives output file output.txt as:
line 3

Can someone suggest me a solution?

#include <fstream>
#include <string>
#include <vector>
#include <algorithms>

int main(int argc, char* argv[])
{
std::ifstream in("in.txt");
if(in) {
std::vector<std::string> v;
while(!in.eof() && in) {
std::string str;
std::getline(in,str,'\n');
v.push_back(str);
}
std:fstream out("out.txt");
if(out) {
std::copy(v.rbegin(),v.rend(),
std:stream_iterator<std::string>(out,"\n"));
}
}
return 0;
}

And if it is a huge file, better split your output to multiple files
(clearing the vector after every iteration) and in the end, just append
those files in reverse order.

 

[neo]

Thanks for the solution but the thing is i need to write it in C, not C++.
-neo

neo skrev:

Hello everyone,
I want to write a function that takes a simple text file as input and
outputs a file such that the last line in the input file becomes the
first line in the output file and the first line of the input becomes the
last line of output.

I had written this function as:

But on giving input file input.txt as:
line 1
line 2
line 3

it gives output file output.txt as:
line 3

Can someone suggest me a solution?

#include <fstream>
#include <string>
#include <vector>
#include <algorithms>

int main(int argc, char* argv[])
{
std::ifstream in("in.txt");
if(in) {
std::vector<std::string> v;
while(!in.eof() && in) {
std::string str;
std::getline(in,str,'\n');
v.push_back(str);
}
std:fstream out("out.txt");
if(out) {
std::copy(v.rbegin(),v.rend(),
std:stream_iterator<std::string>(out,"\n"));
}
}
return 0;
}

 

[Rolf Magnus]

Plese don't top-post.

Thanks for the solution but the thing is i need to write it in C, not C++.

Why are you asking in a C++ newsgroup then instead of a C newsgroup?

 

[news.onet.pl]

#include <algorithm>

I tried using the code in Borland Builder 6.0 and I get the error:
'ostream_iterator' is not a member of 'std'.
Is it included in other file
PZ