Determine if a string is numeric: Difference between revisions
Determine if a string is numeric (view source)
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=={{header|6502 Assembly}}==
For this program, a valid numeric string literal consists of only numbers (ascii $30-$39), up to one <i>leading</i> minus sign, and no more than one decimal point. Anything else, including the null string, is considered non-numeric.
Macros used:
<pre>
macro loadpair,regs,addr
lda #<\addr
sta \regs
lda #>addr
sta \regs+1
endm
macro pushY
tya
pha
endm
macro popY
pla
tay
endm
</pre>
The code:
<lang 6502asm>*=$0801
db $0E,$08,$0A,$00,$9E,$20,$28,$32,$30,$36,$34,$29,$00,$00,$00 ;required init code on commodore 64 floppy disks
*=$0810
lda #$0e
jsr chrout ;required for my printing routine to work.
z_HL equ $02
z_L equ $02
z_H equ $03
z_B equ $04
loadpair z_HL,TestString0
jsr isStringNumeric
loadpair z_HL,TestString1
jsr isStringNumeric
loadpair z_HL,TestString2
jsr isStringNumeric
loadpair z_HL,TestString3
jsr isStringNumeric
loadpair z_HL,TestString4
jsr isStringNumeric
loadpair z_HL,TestString5
jsr isStringNumeric
loadpair z_HL,TestString6
jsr isStringNumeric
loadpair z_HL,TestString7
jsr isStringNumeric
loadpair z_HL,TestString8
jsr isStringNumeric
rts ;return to basic
isStringNumeric:
; input: z_HL = source address
pushY
ldy #0
sty z_B ;our tally for decimal points
checkFirstChar:
lda (z_HL),y
beq notNumeric ;a null string is not a valid number!
cmp #'-'
beq isNegative_OK
cmp #'.'
beq isFloat_OK
and #$30
cmp #$30
beq isNumeral_OK
;else, is not numeric
notNumeric:
popY
jsr PrintString_TextScreen ;prints what's already in z_HL
jsr NewLine
loadpair z_HL,isStringNumeric_Fail
jsr PrintString_TextScreen
jsr NewLine
jmp NewLine
;rts
isNegative_OK:
isNumeral_OK:
iny
jmp loop_isStringNumeric
isFloat_OK:
iny
inc z_B
loop_isStringNumeric:
lda (z_HL),y
beq Terminated_isStringNumeric
cmp #'.'
beq CheckIfDecimalAlreadyOccurred
and #$30
cmp #$30
bne notNumeric
loop_overhead_isStringNumeric:
iny
jmp loop_isStringNumeric
CheckIfDecimalAlreadyOccurred:
lda z_B
bne notNumeric
inc z_B
jmp loop_overhead_isStringNumeric
Terminated_isStringNumeric:
;if we got this far the string is numeric.
popY
jsr PrintString_TextScreen ;prints what's already in z_HL
jsr NewLine
loadpair z_HL,isStringNumeric_Pass
jsr PrintString_TextScreen
jsr NewLine
jmp NewLine
;rts
isStringNumeric_Pass:
db "IS NUMERIC",0
isStringNumeric_Fail:
db "IS NOT NUMERIC",0
TestString0:
db 0
TestString1:
db "123",0
TestString2:
db "-30",0
TestString3:
db "123.45",0
TestString4:
db "-123.45",0
TestString5:
db "ABCDE",0
TestString6:
db "-34-5",0
TestString7:
db "1.000.000",0
TestString8:
db ".23456",0</lang>
{{out}}
<pre>
ready.
load"*",8,1:
searching for *
loading
ready.
run
IS NOT NUMERIC
123
IS NUMERIC
-30
IS NUMERIC
123.45
IS NUMERIC
-123.45
IS NUMERIC
ABCDE
IS NOT NUMERIC
-34-5
IS NOT NUMERIC
1.000.000
IS NOT NUMERIC
.23456
IS NUMERIC
ready.
</pre>
=={{header|8th}}==
<lang Forth>: number? >n >kind ns:n n:= ;</lang>
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