Hello there:

I am having some problems using scanf to get a string of 22 characters from a serial port.

I think the problem is that the string has some blank characters on it, so scanf will stop in each blank character and get 2 or 3 strings instead of only 1.

The string is something like this "N____0.000_g__CRLF" where the '_' are blank characters (20 hex).

Now with scanf I am getting something like this:

N

0.000

g

I have sorted this problem with a for loop and getc() but I prefer to do it with scanf.

Is there any way to indicate scanf that the string will length 22 characters and get the 22 in a shot??

Regards,

Rafa.

Show us your code with the scanf call.

Edit: actually, I think what you want is "%22c". But it's a pretty ineffective way of using scanf. Why not tell it to parse the line for the data that's in there (e.g. the number)?

Ok, here it is a bit of the code:

int main() {

    serie_bal.baud(19200);

    while (1) {

        serie_bal.scanf("%s\n", &strBalanza);//Capturamos cadena de balanza

.....

I receive a 22 characters string every 100ms, and because scanf is a blocking function (i think) it would be perfect to catch the string with it. (it will wait until a string comes in).

With this code, it works, but the problem is that the scanf catches a string every blank character it founds. If the string wouldnt have blank characters it would run perfect. I need advise on how to get the entire string (22characters) with blank spaces and all.

Hope you can help me.

Regards.

EDIT:

I have tried %22s, will try %22c to see if it works. Sorry but i dont know what is "to parse". My english is so limited. BTW, I need all the information in the string, because it depends on how many blank characters are there to do one or other thing later...

why dont you replace the "_" (blank) with a comma?

I wouldn't use scanf at all. If there are line breaks and reasonable line lengths I would use fgets. If it is really just characters in blocks of 22, I would use fgetc or even fread. Since there are spaces in your data, it suggests that there is an underlying structure, in that case I would first get the sting (22 chars) and then use sscanf to parse the string. scanf just does not do well with unexpected input.