Plz anyone tell me what is the problem with this code coach problem code?

Question

#include <stdio.h>
#include <string.h>

int main() {
char str[100];
gets(str);
char ans[100];
int len = strlen(str);
int i,j,k,temp;
j=0;
for(k=0;k<len/2;k++)
{
temp = str[k];
str[k] = str[len-k-1];
str[len-k-1] = temp;
}
for(i=0;i<len;i++)
{
if((str[i]>=65 && str[i]<=90) || (str[i]>=97 && str[i]<=122) || str[i]==32)
{
ans[j]=str[i];
j++;
}
}
puts(ans);
return 0;
}

Answer 1

The problem is that the string in `ans` is not null-terminated, so depending on what values where in that memory beforehand, you write more characters than you actually want. Either zero-initialize the array at the start or explicitly store a null character at the end of the string to make it work, i.e

char ans[100] = {0};

or

ans[j] = '\0';
puts(ans);

Answer 2

I tested your snippet with default

Answer 3

Did it run?

Answer 4

I mean did it give the required output?

Answer 5

I tested your snippet with default sample "d89%l++5r19o7W *o=l645le9H"

It did run, and it did output "Hello World"

I don't know why you get a problem, the only possible issue I see here is the use of gets() function which is deprecated. People avoid using gets() and use fgets() instead for now.

http://www.cplusplus.com/reference/cstdio/fgets/

(Edited)