strange character is output to the terminal - c

Question

I'm beginer in C/C++ programming.
This is my program that displays binary numbers in ascending order in the terminal (I'm compiling in Linux Mint).
#include <stdio.h>
#include <math.h>
#include <stdbool.h>
#include <string.h>
void reverse(char *x, int begin, int end)
{
char c;
if (begin >= end)
return;
c = *(x+begin);
*(x+begin) = *(x+end);
*(x+end) = c;
reverse(x, ++begin, --end);
}
int main()
{
unsigned int bitCount;
unsigned int naborCount;
printf("Число битов в наборе: ");
scanf("%d", &bitCount);
printf("\n");
naborCount = pow(2, bitCount);
char naborStr[bitCount*2];
for(int i = 0; i<naborCount; i++)
{
for(int j = 0; j<bitCount; j++)
{
if((i & (1<<j))==0)
{
strcat(naborStr, "0 ");
}
else
{
strcat(naborStr, "1 ");
}
if(j == bitCount-1)
{
reverse(naborStr, 0, strlen(naborStr)-1);
printf("%s \r\n", naborStr);
memset(naborStr, 0, sizeof(naborStr));
}
}
}
return 0;
}
This is what I see in the terminal
Where did this symbol come from? How to solve it?

Answer 1

C strings are null terminated.
The %s specifier searches for a null termination.
In your case it keeps on printing until it finds one, so you get some random symbols.
Try making use of null character at the end of the string and check.
Have a look at the following implementation:
#include <stdio.h>
#include <math.h>
#include <stdbool.h>
#include <string.h>
void reverse(char *x, int begin, int end)
{
char c;
if (begin >= end)
return;
c = *(x+begin);
*(x+begin) = *(x+end);
*(x+end) = c;
reverse(x, ++begin, --end);
}
int main()
{
unsigned int bitCount;
unsigned int naborCount;
printf("Число битов в наборе: ");
scanf("%d", &bitCount);
printf("\n");
naborCount = pow(2, bitCount);
char naborStr[bitCount*2 + 1]; //Increased size by 1 for null character
for(int i = 0; i<naborCount; i++)
{
for(int j = 0; j<bitCount; j++)
{
if((i & (1<<j))==0)
{
strcat(naborStr, "0 ");
}
else
{
strcat(naborStr, "1 ");
}
if(j == bitCount-1)
{
reverse(naborStr, 0, strlen(naborStr)-1);
naborStr[bitCount*2 +1] = '\0'; //Appending null character
printf("%s \r\n", naborStr);
memset(naborStr, 0, sizeof(naborStr));
}
}
}
return 0;
}