Special array reversal,reverse the string without affecting the positions of the special characters: C program

Special array reversal

Given a string S, containing special characters and all the alphabets, reverse the string without

affecting the positions of the special characters. 

#include <stdio.h>

#include <string.h>

main()

{

char s[20],temp;

int i=0,j;

gets(s);

j=strlen(s)-1;

while(i<j)

{

if(isalpha(s[i]) && isalpha(s[j]))

{

temp=s[i];

s[i]=s[j];

s[j]=temp;

i++;j--;

}

else if(isalpha(s[i]))

j--;

else

i++;

}

puts(s);

}

Output: