#include <stdio.h>

#define MAX 999

/*

exercise 1-19: write a function revers(s) that reverses a string (s). Use it to write a program that reverses its input a line at a time.

*/

char revers(char s[]);

int getnextline(char s[],int lim);

static int len = 0;

int main()

{

char s[MAX];

int d = 0;

while ( (len = getnextline(s, MAX) )> 1 )

{

// printf("len equals: %d", len);

revers(s);

// for ( d = 0; d <= len ; d++ )

// printf("s[%c] equals %c \n", d, s[d]);

printf("%s\n", s);

}

return 0;

}

char revers(char s[])

{

int i, j;

// int length = 0;

// get length of string..

// for ( length = 0; s[length] != '\0'; length++ )

// ;

// printf("length equals: %d \n ", len );

// temp string...

char tempstr[len];

while ( s[len] == '\0' || s[len] == '\n' )

--len;

// printf("length equals: %d \n ", len );

// i equals length (including '\0'), j starts from tempstr[0] ...

for ( i = (len ) , j = 0; i >= 0; i-- )

{

// if string[last] is '\0' || '\n', do nothing, but stil i-- (reduce length).

// else tempstr[first] equals s[last]

// else

tempstr[j] = s[i];

// increment s[first]...

++j;

// }

}

// append '\0' to s...

tempstr[j] = '\0';

// copy temp string back to string

for ( i = 0; tempstr[i] != '\0'; i++ )

s[i] = tempstr[i];

s[i] = '\0';

// return s;

}

/* getnextline: read a line into s, return length */

int getnextline(char s[],int lim)

{

int c, i;

for (i=0; i < lim-1 && (c=getchar())!=EOF && c!='\n'; ++i)

s[i] = c;

if (c == '\n')

;

{

s[i] = c;

++i;

}

s[i] = '\0';

return i;

}