Second code is showing an error when I entered something as an input

Answer 1

What code ?

Answer 2

You will get only warnings not errors..
Use fgets() instead of gets();
Like ex:
fgets(a, 100,stdin);

gets() is not recommended when input is more length than its array size, it leads to unwanted results.. So hence warning....

Answer 3

fgets(a,100,stdin);

Do not use gets and you can read about it on web to find the reason.

Answer 4

#include <stdio.h>

int main() {
char a[100];

gets(a);

printf("You entered: %s", a);

return 0;
}
This one