Problems with printf or INT/INT8

[KeithWard]

I have had some difficulty lately with either int or int8 acting like a 7 bit or a signed 8 bit when using printf with an LCD.

I will get the correct values up to 127, after that the values switch to -128 and then work back to 127 for the full count of 255. I have tried similar experiments with just lcd_putc without the same problem yet I have not found any similar problems posted on this forum with this specificity.

Why is this happening? The code is *very* simple ...

Disclaimer:
I am citing this code from memory and not pasteing the *actual* code so any typos should not necessarily be construed as the *real* problem.

void main () {

int i=0

while (TRUE) {
for (i=32;i<256;i++) {
printf (lcd_putc,"Char Dec Hex\n");
printf (lcd_putc,"\%c \%d \%X",i,i,i);
delay_ms (1000);
lcd_putc("\f");
} // End For
} // End While

} // End Main
___________________________
This message was ported from CCS's old forum
Original Post ID: 13865

[R.J.Hamlett]

:=I have had some difficulty lately with either int or int8 acting like a 7 bit or a signed 8 bit when using printf with an LCD.
:=
:=I will get the correct values up to 127, after that the values switch to -128 and then work back to 127 for the full count of 255. I have tried similar experiments with just lcd_putc without the same problem yet I have not found any similar problems posted on this forum with this specificity.
:=
:=Why is this happening? The code is *very* simple ...
:=
:=Disclaimer:
:=I am citing this code from memory and not pasteing the *actual* code so any typos should not necessarily be construed as the *real* problem.
:=
:=void main () {
:=
:= int i=0
:=
:= while (TRUE) {
:= for (i=32;i<256;i++) {
:= printf (lcd_putc,"Char Dec Hex\n");
:= printf (lcd_putc,"\%c \%d \%X",i,i,i);
:= delay_ms (1000);
:= lcd_putc("\f");
:= } // End For
:= } // End While
:=
:=} // End Main
This is happening, because you are using the wrong qualifier in the printf statement. \%d, tells the function to expect a _signed_ integer. Hence the eighth bit will be treated as a sign bit. The qualifier to print an unsigned integer, is \%u...

Best Wishes
___________________________
This message was ported from CCS's old forum
Original Post ID: 13868

[KeithWard]

Nice catch! So much for my memory of C and RTFM!

Thanks!

:=:=I have had some difficulty lately with either int or int8 acting like a 7 bit or a signed 8 bit when using printf with an LCD.
:=:=
:=:=I will get the correct values up to 127, after that the values switch to -128 and then work back to 127 for the full count of 255. I have tried similar experiments with just lcd_putc without the same problem yet I have not found any similar problems posted on this forum with this specificity.
:=:=
:=:=Why is this happening? The code is *very* simple ...
:=:=
:=:=Disclaimer:
:=:=I am citing this code from memory and not pasteing the *actual* code so any typos should not necessarily be construed as the *real* problem.
:=:=
:=:=void main () {
:=:=
:=:= int i=0
:=:=
:=:= while (TRUE) {
:=:= for (i=32;i<256;i++) {
:=:= printf (lcd_putc,"Char Dec Hex\n");
:=:= printf (lcd_putc,"\%c \%d \%X",i,i,i);
:=:= delay_ms (1000);
:=:= lcd_putc("\f");
:=:= } // End For
:=:= } // End While
:=:=
:=:=} // End Main
:=This is happening, because you are using the wrong qualifier in the printf statement. \%d, tells the function to expect a _signed_ integer. Hence the eighth bit will be treated as a sign bit. The qualifier to print an unsigned integer, is \%u...
:=
:=Best Wishes
___________________________
This message was ported from CCS's old forum
Original Post ID: 13875