Recursive function to reverse order of string?

Question

i have to write a recursive program that allows you to enter a word and then output the string in reverse order. I just am unsure of how to reverse the string ??

Answer 1

include

#include



void reverse(char **s, int start, int last)

{

char tmp;

if (start >= last)

return;

char *s2 = *s;

tmp = s2[start];

s2[start] = s2[last];

s2[last] = tmp;

reverse(s, start + 1, last - 1);

}



int main()

{

char *s = strdup("Hello World");

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

reverse(&s, 0, strlen(s) - 1);

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

}

Answer 2

#include



static void rprint(const char *s);



int main(void)

{

        char s[] = "\?smargorp laivirt hcus gnitirw elbuort evah uoy od yhW";



        rprint(s);

        return 0;

}



static void _rprint(const char *s)

{

        if (!*s)

                return;

        _rprint(s + 1);

        putchar(*s);

}



void rprint(const char *s)

{

        _rprint(s);

        putchar('\n');

}



EDIT: I didn't notice the "enter a word" part. Either way, it's pretty similar to printing a string.



#include



static int revecho(FILE *dstream, FILE *sstream);



int main(void)

{

        return revecho(stdout, stdin) ? 0 : main();

}



static int eol(int c, FILE *stream)

{

        if (c == '\n')

                return 1;

        if (c == '\r') {

                if ((c = getc(stream)) != '\n')

                        ungetc(c, stream);

                return 1;

        }

        return 0;

}



static int _revecho(FILE *dstream, FILE *sstream)

{

        int c = getc(sstream);

        int r = c == EOF;



        if (eol(c, sstream) || r)

                return r;

        r = _revecho(dstream, sstream);

        putc(c, dstream);

        return r;

}



int revecho(FILE *dstream, FILE *sstream)

{

        int r = _revecho(dstream, sstream);



        putc('\n', dstream);

        return r;

}

Answer 3

include

#include

void cswap(char *a, char *b)

{

char T=*a;

*a=*b;

*b=T;



}

void rever(char x[], int beg, int end)

{

if(beg
{

cswap(&x[beg],&x[end]);

return(rever(x,beg+1,end-1));

}



}

int main()

{

char str[]="Ramana";

rever(str,0,5);

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



system("PAUSE");

return 0;

}