1. Printf puzzlement
- Posted by alrobnett Dec 27, 2018
- 925 views
include std/io.e include std/filesys.e include std/error.e include std/console.e include std/graphics.e include std/sequence.e include std/cmdline.e integer key_code sequence test_sequence = "123456789" position (16,50) printf(1, "%7s", {test_sequence}) key_code = wait_key()
Results in:
123456789
Why isn't it:
1234567
2. Re: Printf puzzlement
- Posted by irv Dec 27, 2018
- 961 views
From the docs:
Field widths can be added to the basic formats, e.g. %5d, %8.2f, %10.4s. The number before the decimal point is the minimum field width to be used. The number after the decimal point is the precision to be used for numeric values.
There's no format specifier to clip strings to a given length, so you would need to do that using brackets:
printf(1,"%7s",{test_sequence[1..7]}
Of course, the above would fail if the test_sequence was shorter than 7, so perhaps:
printf(1,"%7s",{test_sequence[1..math:min(7,length(test_sequence))]}
If test_sequence is shorter than 7, then spaces will be added to the start of the string to make it 7 characters long.
printf(1,"%7s",{test_sequence})
Also, look at text:format() and display(), they can often do more than printf() with less coding.
display("[:4]",{test_sequence})
The above will clip the string to the first 4 characters, and will just print it if it has less than 4 characters. See what i mean about doing more with less?
display("[:4>]",{test_sequence})
Above, we right-justify the printout, so blank space(s) are added to the start of the string to make it take up 4 character spaces. There are lots of other possibilities, as well. display() comes in very handy, especially when formatting reports. It's easy to position things exactly where you want them.
3. Re: Printf puzzlement
- Posted by ChrisB (moderator) Dec 28, 2018
- 867 views
Hi, another way
printf(1, "%7.7s", {string})
will print the string into an allocation of 7 spaces, clipped to a maximum of 7 characters, so
1234567
printf(1, "%7.3s", {string})
123
and printf(1, "%-7.3s", {string})
123
the '-' sign says to justify to the left, and the number after the decimal point says how many characters to print within the allocated space. The allocated space can be overflowed, so just watch for that.
Cheers
Chris
Sorry, just noted that that justification didn't show properly
printf(1, "%7.7s", {string})
will print the string into an allocation of 7 spaces, clipped to a maximum of 7 characters, so
1234567
printf(1, "%7.3s", {string})
123
and
printf(1, "%-7.3s", {string})
123
4. Re: Printf puzzlement
- Posted by alrobnett Dec 28, 2018
- 872 views
Thanks Irv and Chris. I had assumed that the decimal point applied only to precision of numerical values. An eye-opener. Allen
5. Re: Printf puzzlement
- Posted by ChrisB (moderator) Dec 28, 2018
- 880 views
Updated
I feel that the art of printf is being lost in this new fangled world of gooey windows.
Chris
