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unexpand.c
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C/C++ Source or Header
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1990-07-19
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2KB
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118 lines
/* unexpand - convert spaces to tabs Author: Terrence W. Holm */
/* Usage: unexpand [ -a ] [ file ... ] */
#include <stdio.h>
#define TAB 8
int column = 0; /* Current column, retained between files */
int spaces = 0; /* Spaces since last tab stop */
int leading_blank = 1; /* Only unexpand leading blanks, */
/* Overruled by -a option */
main(argc, argv)
int argc;
char *argv[];
{
int all = 0; /* -a flag means unexpand all spaces */
int i;
FILE *f;
if (argc > 1 && argv[1][0] == '-') {
if (strcmp(argv[1], "-a") == 0)
all = 1;
else {
fprintf(stderr, "Usage: unexpand [ -a ] [ file ... ]\n");
exit(1);
}
--argc;
++argv;
}
if (argc == 1)
Unexpand(stdin, all);
else
for (i = 1; i < argc; ++i) {
if ((f = fopen(argv[i], "r")) == NULL) {
perror(argv[i]);
exit(1);
}
Unexpand(f, all);
fclose(f);
}
/* If there are pending spaces print them. */
while (spaces > 0) {
putchar(' ');
--spaces;
}
exit(0);
}
Unexpand(f, all)
FILE *f;
int all;
{
int c;
while ((c = getc(f)) != EOF) {
if (c == ' ' && (all || leading_blank)) {
++column;
++spaces;
/* If we have white space up to a tab stop, then output */
/* A tab. If only one space is required, use a ' '. */
if (column % TAB == 0) {
if (spaces == 1)
putchar(' ');
else
putchar('\t');
spaces = 0;
}
continue;
}
/* If a tab character is encountered in the input then */
/* Simply echo it. Any accumulated spaces can only be */
/* Since the last tab stop, so ignore them. */
if (c == '\t') {
column = (column / TAB + 1) * TAB;
spaces = 0;
putchar('\t');
continue;
}
/* A non-space character is to be printed. If there */
/* Are pending spaces, then print them. There will be */
/* At most TAB-1 spaces to print. */
while (spaces > 0) {
putchar(' ');
--spaces;
}
if (c == '\n' || c == '\r') {
column = 0;
leading_blank = 1;
putchar(c);
continue;
}
if (c == '\b')
column = column > 0 ? column - 1 : 0;
else
++column;
leading_blank = 0;
putchar(c);
}
}