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strip_pipe_delimited_fields.c
C
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#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
static char * append (char *field, size_t *size, size_t *len, char c);
static size_t get_field (char **field, size_t *size, FILE *file);
static char const * strip_field (char *field, size_t len);
 
static bool end_of_file = false;
static bool end_of_line;
 
int
main (int argc, char *argv [])
{
char *field = NULL;
FILE *file;
char const *filename;
size_t len;
size_t size = 0;
char const *stripped;
 
if (2 != argc) {
printf("Exactly one filename must be specified\n");
return EXIT_FAILURE;
}
 
filename = argv[1];
file = fopen(filename, "r");
if (NULL == file) {
printf("%s: file not found\n", filename);
return EXIT_FAILURE;
}
 
NEW_LINE:
len = get_field(&field, &size, file);
stripped = strip_field(field, len);
if (strcmp("", stripped)) {
printf("%s", stripped);
if (end_of_file) {
goto EXIT;
}
} else {
if (end_of_file) {
goto EXIT;
}
printf("null");
}
 
while (!end_of_line) {
len = get_field(&field, &size, file);
printf("|%s", strip_field(field, len));
if (end_of_file) {
goto EXIT;
}
}
 
printf("\n");
goto NEW_LINE;
 
EXIT:
free(field);
 
fclose(file);
 
return EXIT_SUCCESS;
}
 
char *
append (char *field, size_t *size, size_t *len, char c)
{
if (*size <= (*len + 1)) {
field = (char *)realloc(field, *size + 64);
*size += 64;
}
 
field[(*len)++] = c;
 
return field;
}
 
size_t
get_field (char **field, size_t *size, FILE *file)
{
int c;
size_t len = 0;
 
end_of_line = false;
c = fgetc(file);
while ('|' != c) {
if ('\n' == c) {
end_of_line = true;
goto EXIT;
}
if (EOF == c) {
end_of_file = true;
goto EXIT;
}
*field = append(*field, size, &len, c);
c = fgetc(file);
}
 
EXIT:
(*field)[len] = '\0';
 
return len;
}
 
char const *
strip_field (char *field, size_t len)
{
size_t b;
size_t e;
 
if (0 == len) {
return field;
}
 
for (b = 0; b < len; ++b) {
if ((' ' != field[b]) && ('\t' != field[b])) {
break;
}
}
 
for (e = len - 1; e > b; --e) {
if ((' ' != field[e]) && ('\t' != field[e])) {
break;
}
}
 
if (e == b) {
field[b] = '\0';
} else {
field[e + 1] = '\0';
}
 
return field + b;
}
 
// Local Variables:
// c-basic-offset: 4
// indent-tabs-mode: nil
// End:
 
// vi: set et ts=4 sw=4 :

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