Write a function reverse(s) that reverses the character string s. Use it to write a program that reverses its input a line at a time.

#include <stdio.h>
#define   MAXLINE    1000    /*maximum input line size */

int getline(char line[], int maxline);
void reverse(char s[]);

/*reverse input lines, a line at a time     */
int main(){
     char line[MAXLINE];     /*current input line */

     while(getline(line, MAXLINE) > 0){
          reverse(line);
          printf("%s", line);
     }
}
/* reverse: reverse string s                  */
void reverse(char s[]){
    int i, j;
    char temp;

    i = 0;
    while (s[i] != '\0')   /*find the end of  string s */
          ++i;
    --i;                  /*back off from '\0'   */
   if (s[i] == '\n')
        --i;            /*leave newline in  place */
   j = 0;
   while (j < i){
         temp = s[j];
         s[j] = s[i];    /*swap the characters */
         --i;
         ++j;
   }
}