Val procedure

Declaration

procedure Val(const S: string; var V; var Code: Word)

Description

Val converts the value represented in the string S to a numerical value or an enumerated value, and stores this value in the variable V, which can be of any integer type (signed or unsigned, sizes from 1 to 8 bytes), floating point type (of any supported size) or any enumerated type. If the conversion is not successful, then the parameter Code contains the index of the character in S which prevented the conversion. The string S is allowed to contain spaces in the beginning.

The string S can contain a number in decimal, hexadecimal, binary or octal format, as described in the language reference. For enumerated values, the string must be the name of the enumerated value. The name is searched case insensitively.

The string can use various radices in addition to a decimal (radix 10) notation:

• $, 0x or x can be used for hexadecimal notation. Allowed characters are 0..9 and A..F (case insensitive)
• & for octal notation. Allowed characters are 0..7.
• % for binary notation. Allowed characters are 0..1.

The conversion to enumerated exists only as of version 2.3.1 (or later) of the compiler.

If S represents a numerical value in decimal notation, or a negative number, then the numerical value must fit into the range of the type of V, otherwise Val will report an error.

If S represents a numerical value in binary, octal or hexadecimal notation, and does not contain a minus sign, then the numerical value must fit into the unsigned counterpart of the type of V and will be casted to the type of V. If not, Val will report an error.

Errors

If the conversion doesn't succeed, the value of Code indicates the position where the conversion went wrong. The value of V is then undefined.

See also

• Str

Example: ex74

Program Example74;

{ Program to demonstrate the Val function. }
Var I, Code : Integer;

begin
  Val (ParamStr (1),I,Code);
  If Code<>0 then
    Writeln ('Error at position ',code,' : ',Paramstr(1)[Code])
  else
    Writeln ('Value : ',I);
end.