Thread: transforming this loop into a recursive function question

i tried to transform this loop

Code:

printf("enter string\n");
 for (i = 0; i < 39 && (ch = getchar()) != '\n' && ch >=0; ++i)
    {
        input2[i] = ch;
    }

    input2[i] = '\0';

	*/

Code:

#include <stdio.h>
void read(input2,i);
int main()
{
    int input2[40];
    read(input2,0);
}
void read(input2,i)
{
	char ch;
	if (i==39)
	{
                    input2[i] = '\0';
	    return ;
	}
               if ((i<39)&&( (ch = getchar()) != '\n') &&( ch >=0))
              {
                   input2[i] = ch;
               }
               read(input2,i+1); 
}

but its not running
its giving me two errors like
(13) : error C2109: subscript requires array or pointer type
why??
(in the edit scren its perfectly intended but when i save it gives me what you see)

Why are you asking so many "recursive" questions?
Especially for things like this which have no business being recursive.

Originally Posted by Salem

Why are you asking so many "recursive" questions?

Hahaha, I laughed out loud at that. But to be fair, if this is transgalactic2's way of getting a grip on recursion, let the experiments fly.

I still say doing the fibonacci set is a terrifically enlightening recursive function exercise.

I don't think there's much value in converting random loops to recursion for learning purposes. I agree with Salem, that it would be more productive to work on directly writing functions that are more 'naturally' recursive.
If you're short of examples of such things, I could give you plenty.

I reckon the useful skill is not going from iterative to recursive, but the other way around.

its for an assignment
i need to change the loop into a recursive function
i tried to build it
but its not working

Code:

#include <stdio.h>
void read(char input2[],int i);
int main()
{
    int input2[40];
    read(input2,0);
}
void read(char input2[],int i)
{
	char ch;
	if (i==39)
	{
       input2[i] = '\0';
	   return ;
	}
    if ((i<39)&&( (ch = getchar()) != '\n') &&( ch >=0))
     {
       input2[i] = ch;
     }
     read(input2,i+1); 
}

but its still not working as this loop

Code:

/*
printf("enter string\n");
 for (i = 0; i < 39 && (ch = getchar()) != '\n' && ch >=0; ++i)
    {
        input2[i] = ch;
    }

    input2[i] = '\0';

	*/

basically what i need is to enter a string in a row and when i press enter
it stops even if the array is not full to the limit.
this loop did exactly that
and i was told that there is no other way to do it

i could use scanf but then again i need to use a loop with a command(which is not allowed) to clean the buffer

??

Code:

void read(char input2[],int i)
{
	char ch;

	ch = getche();
	if( ch != '\r' && ch > 0 && i < 39 )
		input2[i] = ch;
	else
	{
		input2[i] = '\0';
		return;
	}
	read(input2,i+1); 
}

or more sophisticated:

Code:

int read(char input2[], int i);

int main(int argc, char* argv[])
{
	char input2[40];
	input2[read(input2,0)] = '\0';
	
	return( 0 );
}

int read(char input2[], int i)
{
	char ch = getche();
	if( ch != '\r' && ch > 0 && i < 39 )
		input2[i] = ch;
	else
		return( i );
	return( read(input2,i+1) ); 
}

Originally Posted by flexo87

If you want it to stop on enter you should check if the character is equals to '\r' instead of '\0'.

No -- because stdin is opened in text mode, the runtime automatically translates the Windows end-of-line "\r\n" into a single "\n". You should check for '\n' to find the end of line, not '\r'

Originally Posted by brewbuck

No -- because stdin is opened in text mode, the runtime automatically translates the Windows end-of-line "\r\n" into a single "\n". You should check for '\n' to find the end of line, not '\r'

For me it worked only with '\r'.

And both of my proposals worked under each and every condition.

(getchar() wanted always a RETURN to complete - VS 2005)

A for-loop:

Code:

for (int i=0; i<n; ++i) {
    doSomething(i);
}

A direct translation of the above for-loop into recursive form:

Code:

void recursivelyDoSomething(int i, int n) {
    if (i < n) {
        doSomething(i);
        recursivelyDoSomething(i+1, n);
    }
}

...

recursivelyDoSomething(0, n);

Does that help?