I want to write program that prompt the user for one character from the keyboard. For the character entered, classify the character as a number, a letter If user entered "*" then loop again for new value The problem is always show the result is number, which not right when I enter letter. I appreciate any help.
ORG $1000
*read user input
START:
MOVEQ #18,D0
LEA PR1,A1
TRAP #15
*COMPARING
MOVE.B D1,D2
CMP.B #$30,D2 ;if ch less than ASCII '0'
BGE number
CMP.B #$39,D2 ;check if ch greater than ASCII '9'
BLE number
ANDI #$DF,D2 ;CONVERT TO UPPERCASE
CMP.B #65,D2
BGE letter
CMP.B #90,D2
BLE letter
CMP.B #$2a,D1 ;if user enter *
BEQ START ;then loop again to enter new value
number LEA n,A1
JSR P_STR
MOVE.B #5,D0
TRAP #15
letter LEA l,A1
JSR P_STR
MOVE.B #5,D0
TRAP #15
PR1 DC.B 'Enter value: ',0
n DC.B 'Number',0
l DC.B 'Letter',0
INCLUDE 'sample.x68' ; it is the file Prints a string withCR/LF
END START
Your logic is incorrect:
CMP.B #$30,D2 ;if ch less than ASCII '0'
BGE number
CMP.B #$39,D2 ;check if ch greater than ASCII '9'
BLE number
This translates into:
if (ch >= 0x30 || ch <= 0x39) goto number;
What you want is:
if (ch >= 0x30 && ch <= 0x39) goto number;
Which would look something like:
CMP.B #$30,D2
BLT not_number
; We've established that ch>=0x30, now also make sure that it's also <=0x39
CMP.B #$39,D2
BLE number
not_number:
Your letter check might need a similar change; I didn't check that part of the code.