[Resolved] Arrays + Pointers in C

[The Hobo]

I'm trying to write some code that takes input lines and then outputs the last N lines. But all my code is doing is outputting the last line N times. Here's the code:

#include <stdio.h>

int N = 4;
const int MAX_LENGTH = 50;

int main(int argc, char *argv[]) {

	char **lines;
	char *currLine = (char *) calloc(MAX_LENGTH, sizeof (char));

	int start = 0;
	int current = 0;
	int i = 0;

	if (argc > 0 && isdigit(argv[1])) {
		N = argv[1] - '0';

		printf("%d\n", N);
	}

	lines = (char **) calloc (N, sizeof (char *));
	for (i = 0; i < N; i++)
		lines[i] = calloc(MAX_LENGTH, sizeof (char));


	fgets (currLine, MAX_LENGTH, stdin);
	while (! feof (stdin)) {
		*(currLine + strlen(currLine) - 1) = 0;

		if (current == N) {
			current = 0;
			start = 1;
		} else if (start != 0) {
			if (start == N - 1) {
				start = 0;
			} else {
				start++;
			}
		}

		*(lines + MAX_LENGTH * current) = currLine;

		printf("%s\n", *(lines + MAX_LENGTH * current));

		current++;

        fgets (currLine, MAX_LENGTH, stdin);
	}

	// output lines:
	for (i = start; i < N; i++) {
		printf("f[%d]: %s\n", i, *(lines + MAX_LENGTH * i));
	}

	if (start != 0) {
		for (i = 0; i < start; i++) {
			printf("f[%d]: %s\n", i, *(lines + MAX_LENGTH * i));
		}
	}

	free(lines);
	free(currLine);

	return 0;
}

So if the input is:
Line #1
Line #2
Line #3
Line #4

and N = 2, then the output should be:
Line #3
Line #4

What am I screwing up?

[CornedBee]

You need to use strcpy to copy the lines to their buffers.

[The Hobo]

Ah, thanks CB.