Thread: Word backwards! stupid problem!!!

I forgot how to do it, dont know what is wrong, help! Output is some crap...

Code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
char *funk(char *);
int main()

{
	int sranje;
	char niz[30];
	char *n1,*p;

	printf("Recenica: ");
	gets(niz);
	n1=(char *)malloc(sizeof(char)*(sizeof(niz)));
	strcpy(n1,niz);
	p=funk(n1);
	printf("&#37;s", p);

	scanf("%d", &sranje);
}

char *funk(char *n1){

	char *p;
	int i;
	p=(char *)malloc(sizeof(char)*(sizeof(n1)));

	for(i=strlen(n1)-1;i==0;i--)
	{
		p[i]=n1[i];
		
	}
	return p;
}

Code:

gets(niz);

Don't use gets, it's unsafe. Use fgets instead since you can specify a mazimum number of characters to accept from the user.

Code:

n1=(char *)malloc(sizeof(char)*(sizeof(niz)));

First off, you don't need to cast the return value of malloc in C. There is also little reason to malloc a chunk of memory if it's always going to be the same size (30). Maybe you meant:

Code:

n1 = malloc(strlen(niz)+1);

Why have two copies of this word? You already have the initial copy, and the function call is supposed to create another (reversed version). Just use the initial copy to create the reversed version.

Code:

p=(char *)malloc(sizeof(char)*(sizeof(n1)));

Again, you're casting malloc (bad), and sizeof(n1) is always going to be 4 because it's a pointer. sizeof(char) is guaranteed to be 1 so you can omit that. You need to use strlen here:

Code:

p=malloc(strlen(n1)+1);

You really don't need to be messing with dynamic allocation at all, the function can take the address of two arrays of whatever length you want (passed in from main) and create the reversed copy in the second.

Code:

for(i=strlen(n1)-1;i==0;i--)
{
    p[i]=n1[i];
}

For any valid input, the i==0, part means this will always exit the loop without doing anything. Maybe you meant i>=0? You are also copying the data in directly without doing any reversal (and also forgetting the NULL in the reversed version).

Code:

//---------------------------------------------------------------------------

#include <stdio.h>
#include <string.h>
#include <conio.h>

#pragma hdrstop

//---------------------------------------------------------------------------

#pragma argsused

char *ReverseString(char *ptrString)
{
	if(ptrString == NULL)
		return NULL;
	else
	{
		char ptrChar;
		int ptrIndex = 0;
		int ptrLenght = strlen(ptrString);
		for(; ptrIndex < ptrLenght; ptrIndex++)
		{
			ptrChar = ptrString[ptrIndex];
			ptrString[ptrIndex] = ptrString[(strlen(ptrString)-1) - ptrIndex];
			ptrString[(strlen(ptrString)-1) - ptrIndex] = ptrChar;
			ptrLenght--;
		}
		return ptrString;
	}
}
int main(int argc, char* argv[])
{
	char String[] = "yournamehere";
	printf("&#37;s:%s\n",ReverseString("ReverseString"),ReverseString(String));
	printf("Hit any key......\n");
	getch();
	return 0;
}
//---------------------------------------------------------------------------

What to remember is that you need to exchange or swap the characters, so i can save the character to a character variable and then replace it with the last character of the input stirng and then the last character of the input string give the value of the char stored, having in mind to substract one from the length of the string so the loop to end in time.
"I think you will better understand the code rather what i wrote"
LOL.

i get you citizen. it like this, i have this:

Code:

	for(i=strlen(n1)-1;i>=0;i--)// on 30 and every round -1,
	{
	for(j=0;j<strlen(n1)+1;i++)// but this one goes 1 2 3 4 5 6...
	{
		p[j]=n1[i];
	}
		
	}

but this j++, will continue to go up all the way, i need to tell him to stop after one round!

why do you use 2 loops when you need only one?

the second index is easely calculated based on the index of the loop

this is the system:

INDEX
i -> j
5->0
4->1
3->2
2->3
1->4
0->5......

Code:

	for(i=0;i<strlen(n1)+1;i++)
	{
		j=strlen(n1)-1; // THIS GOES OUT!!!
		p[j]=n1[i];
		j--;
		if(j==0)
			break;
	}

something like this, output is messed up!! really im going crazy, this should work!!

Correction: IM SO STUPID!!!!!

it works, but still messed up like, zadar ->==radaz==2

Works perfect now!! Thanks!