Thread: how to know if there is some char in the buffer..

Originally Posted by transgalactic2

if i input 9 chars instead of 8
it returns 1
although it returns 0
how to check for that additional char??

is this the correct way?

Code:

int i;
i=getchar();
if (i!=0)
{
return 0;
}

Where do you input these chars?
Who is "it" that returns 1?
what do you call additional character?

You ask your questions as if everybody have read your previous multipost discussion in whole... You are wrong on this assumption.

your way is incorrect in any way - because if no chars are left getchar will wait till you enter more.

There is no standard IO function that allows you to check if the input buffer has a character available or not.

In a Linux OS, I guess you COULD use select() with the filenumber of stdin as argument [but it will stlll not tell you the complete truth, as stdin is buffered, so it may have buffered some of the data and have data ready to read].

Generally, you have to rely on KNOWING what went on before the getchar() to know if you have more characters to read or not.

--
Mats

So, you return 1 when you have collected size numbers, whether or not you have found the newline at the end of the line.

Again, you need to figure out what the correct order of events is, and how that corresponds to your specifications.

--
Mats

read the whole line and then use strtol to convert each number from the string, thus you know exactly if something left to convert

Originally Posted by vart

read the whole line and then use strtol to convert each number from the string, thus you know exactly if something left to convert

Except if you had read t' other thread, you'd know that no other input functions than scanf(), gets() and getchar() are allowed, and no functions to convert strings.

There is a relatively simple answer to the problem, but I'd like transgalactic2 to figure out the answer, rather than me spoon feeding it.

--
Mats

Originally Posted by matsp

Except if you had read t' other thread, you'd know that no other input functions than scanf(), gets() and getchar() are allowed, and no functions to convert strings.

There is a relatively simple answer to the problem, but I'd like transgalactic2 to figure out the answer, rather than me spoon feeding it.

--
Mats

if some tutor requires to use gets - it is time to look for another one.

scanf could read the whole line, you know?

and convert char to int - could be written manually without any function

and i got another problem that if my input ends with a space
then it doesnt stops on enter
but goes to a new line

Code:

#include <stdio.h>
int read_array(int input[],int i,int size);

int main()
{
	int i;
    int input[40];
    printf("%d\n",read_array(input,0,8));
  for(i=0;i<8;i++)
  {
    printf("%d ",input[i]);
  }
   printf("\n");
   return 0;
}
int read_array(int input[],int i,int size)
{
	int flag,rt,ch;
 	if (i==size)
	{
        
        
	   return 1;
	}
    
    
     flag=scanf("%d",&input[i]);
	 ch=getchar();
	 if ((ch=='\n')&&(i!=size-1))
    {
       return 0;
    }

	 if (ch<0)
    {
		return 0;
	}

	 if (flag==0)
	 {
		 return 0;
	 }
	 else
	 {
	 }
     rt=read_array(input,i+1,size);
	 return rt;
}

Originally Posted by transgalactic2

and i got another problem that if my input ends with a space
then it doesnt stops on enter
but goes to a new line

That's because you are doing the same thing as this

Code:

#include <stdio.h>

int main() {
	int ray[4], i=0;
	printf("Enter: ");
	while (i<4) {
		scanf("%d",&ray[i]);
		i++;
		if (i<4) if (getchar()=='\n') puts("Not enough numbers yet!");
	}
	for (i=0; i<4; i++) printf("%d\n",ray[i]);
	return 0;
}

If you enter "3 45 6SPACE" and then press enter, getchar catches the space and not the newline. But you cannot trap a space, because the spaces are necessary.

What you want, as I tried to tell you yesterday or the day before, is not possible this way. You must write a function using getchar to process the input one character at a time.

If you keep trying to do it your way anyway, you will never run out of little problems like this.

so you say that
i need to save it as a string
and then transform it into an array of integer
but its a very difficult thing to transform

first because
if i read it from left to right
and i will start "-2345" string
how could i know to multiply 2 by 10^3 +3*10^2+4*10^1 +5*10^1
from the starting point i cant know when it ends
and i got this "-" or "+" char
and doing that recursively its impossible