Reputation: 35249
In the following snippet, fscanf() is always returning 0, and not -1 (EOF). As a result, the while loop never quits. Any idea why?
while ((n_items_read = fscanf(ifd, "%la, %la, %la\n", &x, &y, &z)) != EOF) {
...
}
Full code follows:
void parse_test_file(const char* filename) {
double x, y, z;
int n_items_read, n_lines_read;
FILE* ifd = fopen(filename, "r");
if (NULL == ifd) {
fprintf(stderr, "Failed to open %s for reading.\n", filename);
return;
}
n_lines_read = 0;
while ((n_items_read = fscanf(ifd, "%la, %la, %la\n", &x, &y, &z)) != EOF) {
if (n_items_read != 3) {
fprintf(stderr, "n_items_read = %d, skipping line %d\n", n_items_read, n_lines_read);
}
n_lines_read += 1;
}
fprintf(stderr, "Read %d lines from %s.\n", n_lines_read, filename);
fclose(ifd);
}
...and the file in question looks like this. ((FWIW, I tried writing and reading the more familiar %lf format, but that didn't make a difference.)
# this would be the comment line
0x1.069c00020d38p-17, 0x1.0d63af121ac76p-3, 0x1.82deb36705bd6p-1
0x1.d5a86153ab50cp-2, 0x1.10c6de0a218dcp-1, 0x1.c06dac8380db6p-3
0x1.8163b60302c77p-5, 0x1.5b9427fab7285p-1, 0x1.5bccbd0eb7998p-1
Upvotes: 4
Views: 244
Reputation: 121427
The problem is the first line in your input file. *scanf()
doesn't understand the shell style comments. It's just another line in the input file:
# this would be the comment line
When *scanf()
family functions fail due to the format mismatch, the file pointer doesn't move past it. Better idea would be to read line-by-line and then parse it.
Upvotes: 5