Why Am I getting dirty data from strncpy

[marcoshass]

Hi All,

I'm trying to write a very simple program that captures data from stdin and displays it on stdout. Why Am I getting dirty data when the strings are printed ?

(P.S. I know that using the gets function is highly unrecommended, this program is just for testing purposes)

// MultiLine.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#define MAX_SIZE 8096
#define LINE_SIZE 3

void readLines(char *output);

int _tmain(int argc, _TCHAR* argv[])
{
	char output[LINE_SIZE];
	readLines(output);
	getchar();

	return 0;
}

/**
** Lê a entrada através de stdin e de acordo com o tamanho de
** cada linha separa as entradas numerando-as de acordo.
*/
void readLines(char *output) {

	char input[MAX_SIZE];

	int length = 0;

	gets(input);
	length = strlen(input);

	for(int i = 0; i < length; i+= LINE_SIZE) {
		strncpy(output, input + i, LINE_SIZE);
		puts(output);
	}
	
}

** dirty ** output

marcos
mar╠╠╠╠╠8■=
cos╠╠╠╠╠8■=

Thank you very much !!

[brewbuck]

LINE_SIZE of 3 is certainly not big enough. Notice how the first three characters of the output are correct and the rest is garbage? Maybe there's a connection

[bithub]

Read the documentation on strncpy(). It will not null terminate the string when the third argument in less than or equal to the length of the source string.