Skip empty lines - file functions

Skip empty lines - file functions - Printable Version

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+--- Thread: Skip empty lines - file functions (/showthread.php?tid=494071)

Skip empty lines - file functions - dusk - 11.02.2014

Hey, I was wanted to read some data from a file when the server starts.

The file contains empty lines. I thought I will just get an empty string, but "isnull" function says it isn't. I printed out the string as an int and got 13, which is something called "carriage return"...

My question: how do I detect these empty lines?

P.S. The file contains just some data like coordinates and some text. I only load it when my mode starts and speed is not the problem. Also, I don't need key-value, so don't suggest using other file reading/writing systems.

Re: Skip empty lines - file functions - PowerPC603 - 11.02.2014

First read your line and store it into a string, then use

pawn Код:

stock StripNewLine(string[])
{
    new len = strlen(string);
    if (string[0]==0) return ;
    if ((string[len - 1] == '\n') || (string[len - 1] == '\r')) {
        string[len - 1] = 0;
        if (string[0]==0) return ;
        if ((string[len - 2] == '\n') || (string[len - 2] == '\r')) string[len - 2] = 0;
    }
}

From the include file "dutils.inc" (it's included in the server package) to strip newline-characters from your string.
After that you can use "strlen" to check if you have read an empty line.

Re: Skip empty lines - file functions - dusk - 11.02.2014

Thank you! Exactly what I needed.

Re: Skip empty lines - file functions - ColeMiner - 11.02.2014

Another way to check if a line is mostly empty is:

pawn Код:

if (str[0] < ' ')

"\r" and "\n" are both used in various combinations to mean "new line". If you were to do:

pawn Код:

fwrite(fhnd, "hello");
fwrite(fhnd, "there");

The file would look like:

Код:

hellothere

Because no new line characters have been inserted (they must be explicit for file functions, unlike "print" and "printf"):

pawn Код:

fwrite(fhnd, "hello");
fwrite(fhnd, "\r\n");
fwrite(fhnd, "there");

Gives:

Код:

hello
there

Reading the first line back in again will give the string "hello\r\n". Similarly a "blank" line isn't truly blank because it needs these new line characters, so becomes just "\r\n". Of course, neither PowerPC603's method nor my method will regard " \r\n" as a blank line, despite the fact that it only contains whitespace. An alternate function to take that in to account would be:

pawn Код:

bool:IsBlankLine(const str[])
{
    new
        i = 0;
    while ('\0' < str[i] <= ' ') ++i;
    return !str[i];
}

A possibly even more useful function would be:

pawn Код:

bool:GetLine(const str[], &i)
{
    i = 0;
    while ('\0' < str[i] <= ' ') ++i;
    return bool:str[i];
}

Then you can do:

pawn Код:

if (GetLine(str, pos))
{
    // The useful text starts at position "pos".
}