Thread: Help with strings

I have an assignment where I need to scan in strings from a data file (there are about 12 strings). the strings have random numbers in the middle of the words and random punctuation. i need to reprint the strings in reverse order (bottom string at the top, top string at the bottom), and remove all the numbers and punctuation.
Is it possible to scan a string in as a %s, or do I need to scan each character and assign them to the values of a string?
thanks.

Use fgets:

Code:

char buffer[20];
FILE* fpInput;
...
fgets(buffer,sizeof(buffer),fpInput);

Of course you'll need a character array for each line from the file.

I'd recommend using fgets to obtain the strings. I found recursion based on the success of a call to fgets an easy way to reverse the order. And the function isalpha in a simple loop through the string would be useful in determining whether or not to putchar a character.

Let's trim this up a bit and start with something workable.

Code:

#include <stdio.h>
#include <ctype.h>

int main( void)
{
   FILE* file = fopen ( "file.txt", "r" );
   if ( file )
   {
      char line [ 50 ];
      while ( fgets( line, sizeof line, file ) )
      {
         int k;
         for ( k = 0; line [ k ] != '\0'; ++k )
         {
            if ( isalpha ( line [ k ] ) )
            {
               putchar ( line [ k ] );
            }
         }
         putchar ( '\n' );
      }
      fclose ( file );
   }
   return 0;
}

It's much the same as your attempt, but ask questions about any of my changes that you didn't understand. If you need the output to go to a file, use fputc instead of putchar.

You'll notice that the order is not reversed. This is why I mentioned recursion.

[Sorry for the name changes, I'm a little crusty. And you'll need to change your filename back.]

Originally Posted by andy84

this is what i have so far. It is just printing random symbols to the output file.

Code:

#include <ctype.h>
#include <string.h>
#include <math.h>
#include <stdio.h>

#define FILENAME "D:h4ot.txt"
#define INNAME "D:dat4.txt"
#define STRINGSIZE 50

int main( void)
{
char string1 [STRINGSIZE];
char string2 [STRINGSIZE];
char string3 [STRINGSIZE];
int k;


FILE* outfile;
outfile = fopen( FILENAME, "w" );


FILE* infile;
infile = fopen ( INNAME, "r");

while((fgets( string1, STRINGSIZE, infile)))
{
	for (k=0; k<=(strlen(string1)-2); k++)
		{
		if (isalpha(string1[k]))
			{
			putchar(string2[k]);
			}
		}
strcat(string2, string3);
strcpy(string3, string2);
}
fprintf(outfile, "%s", string3);

return 0;
}

thanks

Of course it does. What did you expect it to do? First off, your buffer isn't initialized, so it has a bunch of random crap in it. Next, the first time string3 shows up in your program, you're copying it to another uninitialized buffer, and then copying that back over top of it. Then you print it to a file?

How could it possibly contain something useful?

Quzah.

Originally Posted by andy84

When the program runs, it doesn't come up with any errors, but it doesn't take out any of the numbers like it's supposed to either.

With this "file.txt":

Code:

Pete25.33Moss
Sara78.45Bellum
Harry76Legg
Les34.5Ismoore
April109Showers
June87.345Meadows
Mae68.5Flowers
Guy56Wire
Chris66.335Craft
Slim115.25Pickens

I get this output:

Code:

PeteMoss
SaraBellum
HarryLegg
LesIsmoore
AprilShowers
JuneMeadows
MaeFlowers
GuyWire
ChrisCraft
SlimPickens

And for me it removes the numbers from your example as well.

Code:

asdfsdf
asdfasdfsdfa
asdfsadwe
ewweeerrdf
fddfdfdfdf