small simplification.

This commit is contained in:
NunoSempere 2023-09-09 11:22:41 +02:00
parent 0b01807f10
commit aec062db2e
3 changed files with 18 additions and 21 deletions

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@ -11,7 +11,7 @@
## Comparison with wc.
The GNU utils version ([github](https://github.com/coreutils/coreutils/tree/master/src/wc), [savannah](http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=blob;f=src/wc.c;hb=HEAD)) is a bit over 1K lines of C. It does many things and checks many possible failure modes.
The GNU utils version ([github](https://github.com/coreutils/coreutils/tree/master/src/wc.c), [savannah](http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=blob;f=src/wc.c;hb=HEAD)) is a bit over 1K lines of C. It does many things and checks many possible failure modes.
The busybox version ([git.busybox.net](https://git.busybox.net/busybox/tree/coreutils/wc.c)) of wc is much shorter, at 257 lines, while striving to be [POSIX-compliant](https://pubs.opengroup.org/onlinepubs/9699919799/), meaning it has flags.
@ -35,4 +35,4 @@ The plan9port version of wc ([github](https://github.com/9fans/plan9port/blob/ma
- If it doesn't have arguments, read from stdin.
- [ ] Open files, read characters.
- [ ] Write version that counts lines
- [ ]
- [ ] Document reading from user-inputed stdin (end with Ctrl+D)

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ww

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ww.c
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@ -1,50 +1,47 @@
#include <stdio.h>
#include <unistd.h>
int process_fn(int fn)
int wc(FILE* fp)
{
char c[1];
int seen_word = 0;
int seen_sep_after_word = 0;
int num_words = 0;
int seen_word = 0, seen_sep_after_word = 0, num_words = 0;
int fn = fileno(fp);
while (read(fn, c, sizeof(c)) > 0) {
if (*c != '\n' && *c != ' ' && *c != '\t') {
seen_word = 1;
} else if (seen_word) {
if (*c == '\n' || *c == ' ' || *c == '\t') {
if (seen_word) {
seen_sep_after_word = 1;
}
} else {
// see a separator, but haven't seen a word: do nothing
seen_word = 1;
}
// exercise: what happens if you only track seen_sep,
// instead of seen_sep_after_word?
// test with: $ echo " x x" | ./wc
}
// test with: $ echo " hello world" | ./wc
if (seen_word && seen_sep_after_word) {
num_words++;
seen_sep_after_word = seen_word = 0;
}
}
if (seen_word) {
num_words++;
}
num_words+=seen_word;
printf("%i\n", num_words);
return 0;
}
int main(int argc, char** argv)
{
if (!isatty(STDIN_FILENO)) {
return process_fn(STDIN_FILENO);
if (argc == 1) {
return wc(stdin);
} else if (argc > 1) {
FILE* fp = fopen(argv[1], "r");
if (!fp) {
perror("Could not open file");
return 1;
}
fclose(fp);
return process_fn(fileno(fp));
return wc(fp) && fclose(fp);
} else {
printf("Usage: ww file.txt\n");
printf(" or: cat file.txt | ww\n");
printf(" or: ww # read from user-inputted stdin\n");
}
return 0;
}