Reading/changing an inputted file

[Native]

hey all,

i'm wondering how I would go about inserting a return and spacing/indenting into an output.

i.e. Program reads input file, after every { it inserts a return or /n, indents all the following lines by 4 spaces, program outputs to a txt document.

At the moment i have the following code

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[])
{
	FILE *output;
	char line[256];
	int x;
	FILE * input = NULL;
	output = fopen("output.txt", "w");
	if((input = fopen(argv[1], "r")) != NULL )
	{
		while(fgets(line, 256, input) != NULL)
		{
			fprintf(output, "%s", line);
			char *x = strchr(line, '{');
			if(x)
			{
				printf("/n"); /*here is where i should be inserting /n
			}
		}
	}
	fclose(input);
	fclose(output);
}

Where i have the printf function is where i'm stuck. If anyone could show me what to put here it would be much appreciated as i will use it try and create more rules to for format my output file.

Thanks
native

[CommonTater]

You need to insert the \n into the string BEFORE you write it to your file.

[itsme86]

There's no way to "insert" things (i.e. shift everything after that point to make room) into a file. You'll have to create a new file with the content you want and then, optionally of course, replace the original file with your new "fixed" file.

[Bayint Naung]

				printf("/n"); /*here is where i should be inserting /n

You want to insert newline if encounter { to output file?
Then why are you printing to stdout??
print to your output file!

i.e. Program reads input file, after every { it inserts a return or /n, program outputs to a txt document.

Your current code is still not doing this if input line has more than one {.

[Native]

				printf("/n"); /*here is where i should be inserting /n

You want to insert newline if encounter { to output file?
Then why are you printing to stdout??
print to your output file!


Your current code is still not doing this.

This is what I'm trying to do but am not sure how to go about it, any advice/tips?

[Bayint Naung]

ahha I'm not going to tell you.
Because I'm not quite sure that the code you posted is written by you.(probably your tutor's?)
and you are just to modify it as an assignment perhaps.

[Native]

I'm not quite sure that the code you posted is written by you.(probably your tutor's?)

I wish our lecturer was that helpful, the code is based on other courseworks i have done + help from a friend + forums. Everyone's programs are meant to do the same thing our code is all fairly similar.

Regardless, even if you don't want to post code is there anything you can hint at which might set me in the right direction? I have about 20 firefox tabs open and have been sitting in my computer lab all day trying to work it out and have gotten no-where

[Native]

ok so

 fprintf("output.txt","%c", '/n');

is the one, but the indenting? or well it would be the one if i wasnt getting compile errors :/

[Native]

New code below

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[])
{
	FILE *output;
	char line[256];
	int x;
	FILE * input = NULL;
	output = fopen("output.txt", "w");
	if((input = fopen(argv[1], "r")) != NULL )
	{
		while(fgets(line, 256, input) != NULL)
		{
			char *x = strchr(line, '{');
			if(x)
			{
				fprintf("output.txt","%c", '/n');
			}
		fprintf(output, "%s", line);
		}
	}
	fclose(input);
	fclose(output);
}

Getting the following compile error

exL2.c:18:32: warning: multi-character character constant
exL2.c:18:5: warning: passing argument 1 of ‘fprintf’ from incompatible pointer type /usr/include/stdio.h:335:12: note: expected ‘struct FILE * __restrict__’ but argument is of type ‘char *’

Not sure why this is happening, any thoughts anyone?

[tabstop]

To take the second part first, fprintf doesn't want a filename, it wants a FILE. You have to open the file first. (Don't worry, you can have a bunch of files open. Just open "output.txt" for "w" and go.) Also /n and \n look similar but are not in fact the same.

[itsme86]

'/n' isn't a newline character. You're looking for '\n'.

[Native]

'/n' isn't a newline character. You're looking for '\n'.

Thank you! I should have spotted this, its been a long day with not enough coffee :/

[CommonTater]

I wish our lecturer was that helpful, the code is based on other courseworks i have done + help from a friend + forums. Everyone's programs are meant to do the same thing our code is all fairly similar.

Regardless, even if you don't want to post code is there anything you can hint at which might set me in the right direction? I have about 20 firefox tabs open and have been sitting in my computer lab all day trying to work it out and have gotten no-where

You need to think about your sequence of events...

1) open input file.
2) open output file
3) read a line of text
4) scan for the key character '{"
5) Write out text up to that point
6) Write the newline
7) test for end of line
8) if not EOL loop to step 4
9) write the rest of the line
8) test for end of file
9) if not EOF loop to step 3
10) close output file
11) close input file


You should be able to code that...