how to extract dicimal place

[Packs]

we want to find decimal value exist in the string value .

Example : '34.56'
this is having decimal value > 0 then we want t o print 13.56

Example : '34.00'
in this case we wan to print 34 only .

do we have ready made function in lazarus . I have to write custom function to solve this issue
 

[440bx]

Example : '34.56'
this is having decimal value > 0 then we want t o print 13.56

13.56 ? ... is that a typo ?, if not, what rule is being applied that changes 34.56 into 13.56 ?

[Packs]

yes it is typing mistake . it should be 34.56

[Packs]

Code: Pascal  [Select][+][-]

1.  
2. function CountDecimals(Value: string): string;
3. var
4.   s,s2: string;
5.   p,nInt,nlen: integer;
6. begin
7.   nlen := Length(value);
8.   p := pos(FormatSettings.DecimalSeparator, Value);
9.   if p > 0 then
10.   begin
11.     s2 := copy(Value, p+1,nlen );
12.  
13.     nInt := StrToInt(s2);
14.     if nInt > 0 then
15.       result := Value
16.     else
17.       result := copy(Value, 1, p-1);;
18.   end;
19. end;
20.  

I have created custom founction

[Paolo]

And if the input is 13.50 you want as output 13.50 or 13.5 ?

[KodeZwerg]

I have created custom founction

It has errors.

Code: Pascal  [Select][+][-]

1. program Project1;
2. {$IFDEF MSWINDOWS}{$APPTYPE CONSOLE}{$ENDIF}
3.  
4. uses
5.   SysUtils;
6.  
7. type
8.   TNumberType = (ntInvalid, ntFloat, ntInteger);
9.   TNumber = record
10.     FType: TNumberType;
11.     FInteger: Integer;
12.     FFloat: Double;
13.     FString: string;
14.   end;
15.  
16. function TryToNumber(const AValue: string; out AOut: TNumber): Boolean;
17. var
18.   i: Double;
19.   s: string;
20. begin
21.   Result := False;
22.   AOut.FType := ntInvalid;
23.   AOut.FFloat := 0.0;
24.   AOut.FInteger := 0;
25.   AOut.FString := '0';
26.   if TryStrToFloat(AValue, i) then
27.     begin
28.       if Frac(i) = 0.0 then
29.         begin
30.           AOut.FType := ntInteger;
31.           AOut.FInteger := Trunc(i);
32.           AOut.FString := IntToStr(Trunc(i));
33.         end
34.         else
35.         begin
36.           AOut.FType := ntFloat;
37.           AOut.FFloat := i;
38.           AOut.FString := FloatToStrF(i, ffFixed, 16, 2);
39.         end;
40.       Result := True;
41.       Exit;
42.     end;
43.   if ((Pos('.', AValue) <> 0) and (FormatSettings.DecimalSeparator <> '.')) then
44.     begin
45.       s := AValue.Replace('.', ',', [rfReplaceAll]);
46.       if TryStrToFloat(s, i) then
47.         begin
48.           if Frac(i) = 0.0 then
49.             begin
50.               AOut.FType := ntInteger;
51.               AOut.FInteger := Trunc(i);
52.               AOut.FString := IntToStr(Trunc(i));
53.             end
54.             else
55.             begin
56.               AOut.FType := ntFloat;
57.               AOut.FFloat := i;
58.               AOut.FString := FloatToStrF(i, ffFixed, 16, 2);
59.             end;
60.           Result := True;
61.           Exit;
62.         end;
63.     end;
64.   if ((Pos(',', AValue) <> 0) and (FormatSettings.DecimalSeparator <> ',')) then
65.     begin
66.       s := AValue.Replace(',', '.', [rfReplaceAll]);
67.       if TryStrToFloat(s, i) then
68.         begin
69.           if Frac(i) = 0.0 then
70.             begin
71.               AOut.FType := ntInteger;
72.               AOut.FInteger := Trunc(i);
73.               AOut.FString := IntToStr(Trunc(i));
74.             end
75.             else
76.             begin
77.               AOut.FType := ntFloat;
78.               AOut.FFloat := i;
79.               AOut.FString := FloatToStrF(i, ffFixed, 16, 2);
80.             end;
81.           Result := True;
82.           Exit;
83.         end;
84.     end;
85. end;
86.  
87.  
88. function CountDecimals(Value: string): string;
89. var
90.   s,s2: string;
91.   p,nInt,nlen: integer;
92. begin
93.   nlen := Length(value);
94.   p := pos(FormatSettings.DecimalSeparator, Value);
95.   if p > 0 then
96.   begin
97.     s2 := copy(Value, p+1,nlen );
98.  
99.     nInt := StrToInt(s2);
100.     if nInt > 0 then
101.       result := Value
102.     else
103.       result := copy(Value, 1, p-1);;
104.   end;
105. end;
106.  
107. var
108.   s: string;
109.   LNum: TNumber;
110. begin
111.   WriteLn('');
112.   WriteLn('KodeZwerg:');
113.   WriteLn('');
114.  
115.   s := '12.34';
116.   if TryToNumber(s, LNum) then
117.     WriteLn(s, ' -> ', LNum.FString)
118.     else
119.     WriteLn(s, ' could not be converted!');
120.  
121.   s := '56,78';
122.   if TryToNumber(s, LNum) then
123.     WriteLn(s, ' -> ', LNum.FString)
124.     else
125.     WriteLn(s, ' could not be converted!');
126.  
127.   s := '9.00';
128.   if TryToNumber(s, LNum) then
129.     WriteLn(s, ' -> ', LNum.FString)
130.     else
131.     WriteLn(s, ' could not be converted!');
132.  
133.   s := '99,00';
134.   if TryToNumber(s, LNum) then
135.     WriteLn(s, ' -> ', LNum.FString)
136.     else
137.     WriteLn(s, ' could not be converted!');
138.  
139.   s := 'abc';
140.   if TryToNumber(s, LNum) then
141.     WriteLn(s, ' -> ', LNum.FString)
142.     else
143.     WriteLn(s, ' could not be converted!');
144.  
145.   WriteLn('');
146.   WriteLn('Team Prakash:');
147.   WriteLn('');
148.  
149.   s := '12.34';
150.   WriteLn(s, ' -> ', CountDecimals(s));
151.   s := '56,78';
152.   WriteLn(s, ' -> ', CountDecimals(s));
153.   s := '9.00';
154.   WriteLn(s, ' -> ', CountDecimals(s));
155.   s := '99,00';
156.   WriteLn(s, ' -> ', CountDecimals(s));
157.   s := 'abc';
158.   WriteLn(s, ' -> ', CountDecimals(s));
159. {$IFDEF MSWINDOWS}ReadLn; {$ENDIF}
160. end.

Output:

KodeZwerg:

12.34 -> 12,34
56,78 -> 56,78
9.00 -> 9
99,00 -> 99
abc could not be converted!

Team Prakash:

12.34 ->
56,78 -> 56,78
9.00 -> 56,78
99,00 -> 99
abc -> 99

And if the input is 13.50 you want as output 13.50 or 13.5 ?

In my case you still have values and be able to format however you want.
By default I round to two digits after seperator to having a same look (for floats)

[jamie]

Code: Pascal  [Select][+][-]

1. Function ValidDecOnly(S:String; aPad:Boolean=False):String;
2. Var
3.   I:Integer;
4. Begin
5.   I:= Pos(FormatSettings.DecimalSeparator,S);
6.   If I<>0 Then
7.   Begin
8.    IF StrTOInt(Copy(S,I+1,4)+'0')=0 Then
9.      Result := Copy(S,1,I-1)
10.    else
11.    Begin
12.      Result := S;
13.      // Optional padding;
14.      If APad Then
15.      While Length(Copy(Result,I+1,4))<2 DO Result := Result+'0';
16.    end;
17.   end else Result := S;
18. end;                                        
19.  

I think that should do what you need.

[Kays]

Sigh. One fundamental mistake: Your implementations are attempting to convert a string into a numeric value. The “correct” implementation: You need to perform string inspection only. Example: '-99999999999999999999.000' should yield '-99999999999999999999' (despite any potential overflows).

Prakash has not stated he intends to perform calculations “with strings”, nor has it been established the given strings strictly draw from the domain of real or integer.

The easiest solution is a one-liner using tStringHelper:

Code: Pascal  [Select][+][-]

1. uses
2.         sysUtils;
3. var
4.         s: ANSIString;
5. begin
6.         s := '-99999999999999999999.000';
7.         writeLn(s.trimRight('0.'));
8. end.

[jamie]

It would be better of course to scan right to left using POS. I've seen cases where the separator for the thousands is also the same for the fractions, but only 2 digits.

So, one could extend PosEX to use a -1 as the starting position to indicate a scan right to left should be done or any (-) offset starting from the right to left.

  I don't see anything in the docs about this being able to perform this option now, so I assume it does not.

 I think this would be better than creating a new function just for this.