I've written a program that takes three arguments, the first two of
which are the input file and output file, respectively, and the last
of which is the greatest number of characters you can allow in a line.
Code follows.
/* 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 */
Please note that my program counts the tab character ('\t') as a
single character, although different editors will display it in
different ways. Some will expand it to four spaces, others to eight,
and so on. You shouldn't have any trouble with files that contain no
tabs.
Also note that the carriage return character ('\r') is always
discarded.
If you have any difficulty compiling or running this program, please
let me know so that I have a chance to meet your needs before you rate
my answer.
Cheers,
leapinglizard |
