Thread: reversing a string using pointers

hello everyone,
everything seems to be right in this program except that the puts() function does not print anything.please help!

Code:

/*c program to reverse a string using pointer*/
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
	  char *str,*revstr;
	  char astr[20],arevstr[20];
	  int i,j;
	  printf("\n Enter the string:");
	  gets(astr);
	  str=&astr[0];/*putting the address of astr in str pointer*/
	  j=0;/*is required later in loop1*/
	  revstr=&arevstr[0];/*putting the address of arevstr in revstr pointer*/
	  for(i=strlen(astr);i>=0;i--)/*loop1:using pointers to put the contents of
											  str in revstr in reversed manner*/
	  {
			 *(revstr+j)=*(str+i);
			 printf("%c",*(revstr+j));/* seeing whether the assignment is correct*/
			 j++;
	  }
	  for(j=0;j<=strlen(astr);j++) /*loop2:putting revstr pointer values on array
											  arevstr*/
	  {
			 arevstr[j]=*(revstr+j);
			 printf("%c",arevstr[j]);/*again seeing whether the assignment is
												correct*/
	  }
	  arevstr[j]='\0';/*making arevstr a string*/
	  printf("\n The reversed string is:");
	  puts(arevstr);/*THE PROBLEM:nothing prints here*/
	  getch();
}

You can do this without a second array.

Using your existing code though the problem is on line 15. i+strlen(astr) points to the strings terminating '\0' which you are then copying into the secondary array as its first character. So the secondary arrary's first character in '\0' which is an empty string.

Originally Posted by SirPrattlepod

You can do this without a second array.

Using your existing code though the problem is on line 15. i+strlen(astr) points to the strings terminating '\0' which you are then copying into the secondary array as its first character. So the secondary arrary's first character in '\0' which is an empty string.

thanks a lot for your help! immediately started working after making i=strlen(astr)-1. went nuts in the morning thinking what had gone wrong.
thanks again!!

thanks a lot for your suggestion. i will be going through the level1 and level 2 sections.