This program was done in c(using visual studio) that wraps lines from a text file (breaking the lines to have a maximum of 40 columns). this program was done as a team(but unable to solve the problem at all). The program does not work according to the requirement.The program does not ask for the input.

/* begin wrap.c */
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#include<ctype.h>

#define MAXLINE 10000
#define MAXWORD 1000

int main(int argc, char* argv[])
{
FILE *inf, *outf;
char c = '\0', cc, d, line[MAXLINE+2], word[MAXWORD+2];
int width, newline = 0, line_pos = 0, word_pos = 0;
if (argc != 4)
{
printf("USAGE: wrap <read_from> <write_to><chars_per_line>\n");
return 0;
}
if (!strcmp(argv[1], argv[2]))
{
printf("ERROR: input and output files must differ\n");
return 0;
}
if (!(inf = fopen(argv[1], "r")))
{
printf("ERROR: can't read from \"%s\"\n", argv[1]);
return 0;
}
if (!(outf = fopen(argv[2], "w")))
{
printf("ERROR: can't write to \"%s\"\n", argv[2]);
return 0;
}
if ((width = atoi(argv[3])) > MAXLINE || width < 1)
{
printf("ERROR: line width must be from 1 to %d, inclusive\n",MAXLINE);
return 0;
}
while (1)
{
d = cc;
c = cc = getc(inf);
if (c == EOF)
{
if (line_pos > 0)
{
line[line_pos] = '\0';
fprintf(outf, "%s\n", line);
}
goto quit;
}
if (c == '\r')
continue;
if (c == '\n')
{
if (d == '\n')
newline = 1;
else
c = ' ';
}
line[line_pos++] = word[word_pos++] = c;
if (isspace(c))
word_pos = 0;
if (word_pos > MAXWORD)
{
word[word_pos] = '\0';
printf("ERROR: \"%s\" exceeds maximum word length (%d)\n",word, MAXWORD);
goto quit;
}
if (newline || line_pos > width)
{
newline = 0;
line_pos -= word_pos;
while (isspace(line[--line_pos]) && line[line_pos] !='\n');
line[line_pos+1] = '\0';
fprintf(outf, "%s\n", line);
strncpy(line, word, word_pos);
line_pos = word_pos;
}
}
quit:;
fclose(outf);
fclose(inf);
return 0;
}
/* end wrap.c */

Hello,
1) use code tags
2) what exactly is the problem? I compiled the code and it seems to work fine. Can you please describe what the program does and how exactly that differs from what you want it to do?
3) you shouldn't return zero if an error occurs

I don't understand this. What input?

this program should take a .txt file from the users storage (the .txt contains some words like "hello this is misterxyz and i am here for help " ) and then the duty of the code is to make words to go into next line (this is called word wrap)... so one told me i needed -s and -w(width) to get the word to split and go to next line..

the output given by the program should be somewhat like and this output is made into another .txt file by the program
"hello
this is
misterxyz and
i am here for
help"

And that is exactly what the program does:
I would say the program is working correctly.
A few details:
1)
why +2?

2)
In the first iteration, the value of cc will be uninitialized. What is the point of the cc variable anyway? It seems redundant.

3) Another potential problem:
what if line_pos == word_pos?

Which program are you using to compile it?
When i use Microsoft visual studio it gives me as command
"USAGE: wrap <read_from> <write_to><chars_per_line>"
press any key to continue....


for the question you asked
1) this will not cause any problem
2) i am not sure about this "cc"
3) the changing in the code didn't make any difference.

I used gcc.

That means that (argc != 4). Program needs 3 arguments to run:
i) the name of the input file
ii) the name of the output file
iii) the max number of characters per line
You need to launch the program from the command line with these arguments.
Alternatively, you may specify these arguments somewhere in the Visual Studio (I don't know where exactly since I don't use VS)


If a word is longer than the desired width, then line_pos will be equal to word_pos at that part of the code.
line[--line_pos] will then access memory just before the begining of line. The fact that the data at that address does not happen to correspond to a whitespace character is just luck and doesn't make it a good programming practice.

1 members found this post helpful.

is there anyway you can fix this problem so that it can compile in VS
(i have noticed one more problem that goto is a global variable and its not good to add global variables into a code.

how to launch the program from the command line?.
suppose that my input file is testwork.txt
and my output file is newtestwork.txt
and let the character per line be 40.....

i have specify the argument in the VS in the project properties "testwork.txt" but i got the same result when i complied it...

The code compiles correctly. What you're getting is a runtime error.

That's right. You should not make your variables global if you can avoid it.
However, goto is not a variable, it's a reserved keyword for jump. goto quit makes the program "jump" to a place marked by a label quit. Excessive usage of jumps is also generally not encouraged, because it can lead to spaghetti code.


1) Open the command line
2) cd to the directory containing your executable
3) execute the program with the arguments as the error message suggests

So, assuming that the executable is called WRAP.EXE and it's in the path C:\PATH\TO\THE\PROGRAM:
There must be 3 arguments. It should be something like Project->Properties->Debug and in the box Command line arguments you just enter all three arguments separated by spaces: testwork.txt newtestwork.txt 40.

1 members found this post helpful.

So here is what i got the error
Run-Time Check Failure #3-the variable "cc" is used without being initialized

After the placing the arguments in the Command Line arguments, the working started to work even it made the newtestwork.txt but the program crashed saying "Run-Time Check Failure #3-the variable "cc" is used without being initialized"

Just initialize the cc variable when you declare it, something like

or, even better, remove it, because it serves no purpose whatsoever.

2 members found this post helpful.

Is there any way we can get rid of the "goto" without harming the code?

What i mean is that the program works now correctly, however i was thinking to remove the "goto" from the whole code, how will the code change if goto is removed completely?

you can either replace the goto quit by a break statement, or you can paste the

where in the place of the goto statements. Once you replace the gotos, you may also remove the quit: label.