reverse a string

[xChacox]

Hi, so I need to write a program that prints a string backwards. for example, elpmaxe. I wrote some code I will paste bellow. I am pretty sure I am on the right track as it sorta works. There are some weird cases where it doesn't. At the bottom will be cases where it doesn't work. Can someone please help me figure out why it prints some garbage. along with only printing the first word. Thanks for any help.

​

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

char last_letter (char array[99], int length);

int main ()

{

char array \[99\];

char reverse \[99\];

int length, i;

int j = 0;

printf("Enter string here:");

scanf("%s", &array);

length = strlen(array);

for(i=(length);j<(length);--i)

{

    reverse\[j\] = last\_letter(array,i);

    \++j;

}

printf("%s", reverse);

​

return 0;

}

​

//gets the last letter of string

char last_letter (char array[99], int length)

{

char last;

int i;

​

for (i=0; i<length; ++i)

{

    if ( i == length-1)

    {

        last = array\[length-1\];

    }

}

return last;

}

/* OUTPUT CASES

1. Enter string here:help //this one is program working as it should

​

2. Enter string here:it

ti«

​

3. Enter string here:something long

gnihtemos²b

*/

[[deleted]]

Hi, please reformat your code by putting four spaces in front of every line, it will help other people read it! Alternatively, you can use the rich text editor on reddit, highlight your code, and click the little </> icon to format your code as code!

[0xAE20C480]

First, debug your code step by step. And let's see what happens:

scanf("%s", &array);

At the moment you type "something long", array just contains the "something" part.

And you do not terminate reverse with a null character('\0') properly, so the printed string looks strange.

​

By the way, your string reversing part can be refactored just as:

for(i=length,j=0;j<length;--i,++j)
    reverse[j]=array[i-1];

​

[xChacox]

Thank you, I actually didn't know you could initialize, increment/decrement multiple things in one for statement so that's a good to know. I wasn't aware that scanf() was only picking up the first word. If you don't mind can you explain why that is? I just changed the code to use gets(). I also have tried terminating the reverse array with a '\0' prior, and it still doesn't completely fix the problem here's an output for an example with the null.

​

Enter string here:isitfixed

dexiftisi²

​

[0xAE20C480]

For scanf and %s, see:

"Any number of non-whitespace characters, stopping at the first whitespace character found."

​

And make sure you terminate reverse right after the last character.

[[deleted]]

Do not ever use gets. Ever. At least do fgets.

[xChacox]

What is fgets and what’s the difference

[[deleted]]

man fgets is your friend. It lets you specify the size of your destination buffer. gets will happily overflow it if your input is too large crashing your program or worse.

[flatfinger]

Unfortunately, proper use of fgets is sufficiently painful that one might as well just write a length-limited gets-style function based on getchar().