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Determine if a string is numeric: Difference between revisions
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0.1E-5 => true
50e => false
</pre>
=={{header|Simula}}==
Simula uses the '&' instead of 'e' or 'E' for the exponent part of a floating point decimal number.
<lang simula>BEGIN
BOOLEAN PROCEDURE ISNUMERIC(W); TEXT W;
BEGIN
BOOLEAN PROCEDURE MORE;
MORE := W.MORE;
CHARACTER PROCEDURE NEXT;
NEXT := IF MORE THEN W.GETCHAR ELSE CHAR(0);
CHARACTER PROCEDURE LAST;
LAST := IF W.LENGTH = 0
THEN CHAR(0)
ELSE W.SUB(W.LENGTH,1).GETCHAR;
CHARACTER CH;
W.SETPOS(1);
IF MORE THEN
BEGIN
CH := NEXT;
IF CH = '-' OR CH = '+' THEN CH := NEXT;
WHILE DIGIT(CH) DO CH := NEXT;
IF CH = '.' THEN
BEGIN
CH := NEXT;
IF NOT DIGIT(CH) THEN GOTO L;
WHILE DIGIT(CH) DO CH := NEXT;
END;
IF CH = '&' THEN
BEGIN
CH := NEXT;
IF CH = '-' OR CH = '+' THEN CH := NEXT;
WHILE DIGIT(CH) DO CH := NEXT;
END;
END;
L: ISNUMERIC := (W.LENGTH > 0) AND THEN (NOT MORE) AND THEN DIGIT(LAST);
END;
REAL X;
TEXT T;
FOR X := 0, -3.1415, 2.768&+31, 5&10, .5, 5.&10 DO
BEGIN
OUTREAL(X, 10, 20);
OUTIMAGE;
END;
OUTIMAGE;
FOR T :- "0", "-3.1415", "2.768&+31", ".5", "5&22" DO
BEGIN
OUTTEXT(IF ISNUMERIC(T) THEN " NUMERIC " ELSE "NOT NUMERIC ");
OUTCHAR('"');
OUTTEXT(T);
OUTCHAR('"');
IF T = "0" THEN OUTCHAR(CHAR(9)); OUTCHAR(CHAR(9));
COMMENT PROBE ;
X := T.GETREAL;
OUTREAL(X, 10, 20);
OUTIMAGE;
END;
OUTIMAGE;
X := 5.&10;
!X := 5&;
!X := 5.;
X := .5;
FOR T :- "", "5.", "5&", "5&+", "5.&", "5.&-", "5.&10" DO
BEGIN
OUTTEXT(IF ISNUMERIC(T) THEN " NUMERIC " ELSE "NOT NUMERIC ");
OUTCHAR('"');
OUTTEXT(T);
OUTCHAR('"');
OUTIMAGE;
END;
END
</lang>
{{out}}
<pre>
0.000000000&+000
-3.141500000&+000
2.768000000&+031
5.000000000&+010
5.000000000&-001
5.100000000&+000
NUMERIC "0" 0.000000000&+000
NUMERIC "-3.1415" -3.141500000&+000
NUMERIC "2.768&+31" 2.768000000&+031
NUMERIC ".5" 5.000000000&-001
NUMERIC "5&22" 5.000000000&+022
NOT NUMERIC ""
NOT NUMERIC "5."
NOT NUMERIC "5&"
NOT NUMERIC "5&+"
NOT NUMERIC "5.&"
NOT NUMERIC "5.&-"
NOT NUMERIC "5.&10"
</pre>
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