Help with input conversion.....

hi all, i need to accept a string input, and convert the ouput into a string that consists of only the alphabets typed before in lowercase, and in ascending order. for example, user types in 4ASf4a8!@#jt, and the output is supposed to be aafjst. i dont know how to convert the alphabets into lowercase......can anyone help? thanks!!!

Code:

void sort()
{
	int count;
	char line[20];
	printf("Enter a string (1-20 characters):");
	fflush(stdin);
	gets(line);
	for (count=0;count<strlen(line);count++)
	{
		if (int(line[count])>65)
		{
			//i come here = i'm a letter!!
		}
	}
}

Don't use fflush(stdin);
Don't use gets()

Now that that's out of the way, you can use tolower() from ctype.h to convert a character from uppercase to lowercase.

This looks like an error: if (int(line[count])>65)
Where you trying to typecast line[count]? Right now you're calling a function called int() and passing line[count] to it.

i'm trying to use (int(line[count])>65) so that i can check which inputs are alphabets by using the ASCII table code.

Originally Posted by gundamhamtaro

i'm trying to use (int(line[count])>65) so that i can check which inputs are alphabets by using the ASCII table code.

Just use isalpha() from ctype.h. It will return 1 if the character is alphabetic. You can use islower() if you want to see if it's lowercase.

Have you actually tried to compile (int(line[count])>65)?

yeah, it gave me an "parse error before int" error......

ok, heres what i have now. i still dont know how to check for the correct positioning of the letters though. how do i do that? will strcmp help?

Code:

void sort()
{
	int count,count2;
	char line[20],line2[20];
	printf("Enter a string (1-20 characters):\n");
        scanf("%s",&line);
	for (count=0;count<strlen(line);count++)
	{
		if (isalpha(line[count]) > 0)
		{
			//i come here = i'm a letter!!
			if (islower(line[count]) != 1)
                           //if its not lowercase, change it to lowercase
  			   line2[count2] = tolower(line[count]);
                        else
  			   line2[count2] = line[count];
			count2++;
		}
	}
	printf("Output:\n");
}

Well for starters, your checks are not the greatest. For one, there's no guarintee that isalpha returns > 0 on success. It's just "not zero". That means the implementation could return a negative number if it felt like it. Plus, it's just extra code you don't really even need. The same goes for your islower check. There is no guarintee that it will in fact return one. It's just "non zero", or zero. Furthermore, since you're testing for upper case, why don't you just use isupper?

Code:

if( isalpha( line[ count ] ) )
{
     if( isupper( line[ count ] ) )
    {
        ...
    }
    ...
}

Or, better yet, why even bother checking for isupper or islower at all?

Code:

for (count=0;count<strlen(line);count++)
{
    if( isalpha( line[ count ] ) )
    {
        line2[ count2 ] = tolower( line[ count ] );
        count2++;
    }
}

Then when you've got a string with only lower case letters, sort it.

Quzah.

thanks quzah, but how do i sort alphabets? any hints?

Hint: if('a' > 'b')

ok thanks guys