4 replies to this topic

[skybox]

After reading a chapter on file i/o, I referenced an example in a program of mine that simply will not work. As the title says, I'm having the user enter three different data types, then it saves the information to a file. It is supposed to keep looping until the user just presses enter (At least, I think that's what this segment is supposed to do). Anyway, I've read I shouldn't use the 'feof' function, so I'm hoping someone can offer a better suggesting. Here's the segment:

printf( "Enter ......\n" );

printf( "Enter EOF to end input.\n" );

printf( "? " );

scanf( "%d%s%lf", &account, name, &balance );


while ( !feof( stdin ) )

{

  fprintf( cfPtr, "%d %s %.2lf\n", account, name, balance );

  printf( "? " );

  scanf( "%d%s%lf", &account, name, &balance );

}

Right now, if the user returns an empty line, I get a repeat of '?' on the output until I kill the program. Basically, what I'm wanting is to be able to detect no input given, and work with that condition. I'm certain this isn't the code to do it, but Google searches on the subject haven't turned up anything terribly useful. I hope this is all clear enough, and I really appreciate any and all help in advance. Thanks.

[Ancient Dragon]

On MS-Windows press Ctrl+Z <Enter>

[skybox]

Ancient Dragon said:

On MS-Windows press Ctrl+Z <Enter>

Thanks, Dragon. Yeah, I've decided to scrap that entire approach, as the keystroke is all but obvious to a normal user. How might I go about detecting a blank line entered?

[dbug]

I think there is a problem with scanf call. You try to read an integer, a string and a float. The integer is read correctly, but the remaining line is read as a string, because any character is valid in a string. So the float is "eaten" by the string. The scanf function will only parse 2 arguments: an integer and a string.

[Flying Dutchman]

I think it's better if you assign a letter or number that will terminate your program. Sometimes, to me atleast, happens that I accedently press enter or I press enter too fast and get a blank line. Image if user accedently pressed only enter and he would forget to save data, all his work would be lost.