Hello all. Im having and issue when reading from a .txt file. Some of the lines in it are being skipped by the while loop and I have no idea why. Any insight is greatly appreciated.
Code:#include <stdio.h> #include <string.h> int main(int argc, char *argv) { char str[80]; FILE *fIn; fIn = fopen("./input.txt", "r"); int i; while (fgets(str, 1024, fIn) != NULL) { fgets(str, 1024, fIn); printf("%s",str); } fclose(fIn); }
So ... be the computer. Clear your mind, and walk through the code. As you go, compare how many times you read from the file, compared to the number of times you print something out.
ok i see whats happening, now my question becomes, "how do i detect the end of the file without calling fgets??"
You don't. You must call fgets to detect the end of file. But why call fgets twice? Why not just call it ... once?
> "how do i detect the end of the file without calling fgets??"
You look at the return result of fgets - which you're doing anyway.
> while (fgets(str, 1024, fIn) != NULL)
Will read each line in turn.
HOWEVER!!!!
> char str[80];
If you go around LYING about buffer sizes, you're screwed anyway.
So perhaps pick a decent buffer size (BUFSIZ is a good value to use), and write
while (fgets(str, sizeof(str), fIn) != NULL)
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
