Why there is no output in the following code? (Code below) Please help! 🥺

Question

#include <stdio.h>
#include <string.h>
int main()
{
char p[20];
char *s = "string";
int length = strlen(s);
for (int i = 0; i < length; i++)
p[i] = s[length - i];
printf("%s", p);
return 0;
}
No output. Why? Please explain! 🙏🙏🥺

Answer 1

1. the `strlen` function does not exist. You need to include the <string.h> header file

2. In C, every string ends with a '\0' (null) character. So if the length of a string is 5, its 5th index would be '\0'. Also, the %s specifier in the printf function only prints a string till it encounters '\0'
In your code, the `length` variable stores the value 6 (length of "string" is 6)
Now let's see what will happen in the first iteration of the for loop, when i = 0
p[i] = s[length - i]
=> p[0] = s[6 - 0]
=> p[0] = s[6]
As I said above, the 6th index of a string of length 6 is always a null character. Therefore the 0th index of p is assigned a null character which prevents it from being printed. The fix is simple - simply change `s[length - i ]` to `s[length - i - 1]` so that the null character at the end is ignored

3. Again, in C, every string must end with a null character. But the char array p is not terminated by null. You will need to add a line
p[length] = '\0';

Answer 2

XXX Thanks a lot! 🙏🙏😊😊 Extremely helpful! ☺️☺️