Learning how to Read and output Lines in a file in C - c

Question

I'm trying to write a program that will read a file, and will output the lines of file. It will start with the last line, then will print the second to last line then the last line, second to last line then third to last line and so on and so forth. I almost have it figured out, but
It's the condition of the loop,
change while((c = fgetc(myFile) != EOF)) to while((c = fgetc(myFile)) != EOF)
around the code (c = fgetc....) is off.
Can someone help me fix this?
Thanks.
void tail(FILE* myFile, int num) //Tail function that prints the lines
according to the user specified number of lines
{
int start, line = 0, counter = 0;
char c, array[100];
while((c = fgetc(myFile) != EOF))
{
if(c=='\n')
line++;
}
start = line - num; //Start location
fseek(myFile, 0, SEEK_SET); //Goes to the start of the file
while(fgets(array, 100, myFile) != NULL)
{
if(counter >start)
{
printf("%s",array); //Prints the string
}
counter++;
}
fclose(myFile); //Closes the file
}

Answer 1

The first issue I see is this idiom:
while((c = fgetc(myFile) != EOF))
has the parens wrong, it should be:
while ((c = fgetc(myFile)) != EOF)
Also, this count:
start = line - num; //Start location
has an off-by-one error:
int start = line - num - 1; // Start location
Beyond that, your array seems too small for general text line processing:
char c, array[100];
Putting it all together with a few style tweaks, we get:
// Tail function that prints the lines
// according to the user specified number of lines
void tail(FILE *myFile, int num)
{
int line = 0;
char c;
while ((c = fgetc(myFile)) != EOF)
{
if (c == '\n')
{
line++;
}
}
int start = line - num - 1; // Start location
(void) fseek(myFile, 0, SEEK_SET); // Go to the start of the file
int counter = 0;
char array[1024];
while (fgets(array, sizeof(array), myFile) != NULL)
{
if (counter > start)
{
fputs(array, stdout); // Print the string
}
counter++;
}
fclose(myFile); // Close the file
}