Delphi Basics : StrToInt command

DelphiBasics

StrToInt
Function

Convert an integer string into an Integer value

SysUtils unit

function StrToInt(IntegerString string):Integer;

Description

The StrToInt function converts an Integer string, IntegerString such as '123' into an Integer.

It supports +ve and -ve numbers, and hexadecimal numbers, as prefixed by $ or 0x.

Note that for Delphi 7 and possibly other versions of Delphi, you may omit the 0 before the x for hexadecimal values.

Notes

The EConvertError exception is thrown if there are errors in IntegerString, such as trailing blanks, decimal points, invalid decimal or hexadecimal characters.

Related commands

Integer		The basic Integer type
IntToStr		Convert an integer into a string
StrToInt64		Convert an integer string into an Int64 value
StrToInt64Def		Convert a string into an Int64 value with default
StrToIntDef		Convert a string into an Integer value with default

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Example code : Converting decimal and hexadecimal numbers

var
  A, B, C, D, E, F : Integer;

begin
  A := 32;
  B := StrToInt('100');    // '100' string converted to 100 integer
  C := StrToInt('  -12');  // Leading blanks are ignored
  D := StrToInt('$1E');    // Hexadecimal values start with a '$'
  E := StrToInt('-0x1E');  // ... or with a '0x'
  F := A + B + C + D + E;  // Lets add up all these integers

  ShowMessage('A : '+IntToStr(A));
  ShowMessage('B : '+IntToStr(B));
  ShowMessage('C : '+IntToStr(C));
  ShowMessage('D : '+IntToStr(D));
  ShowMessage('E : '+IntToStr(E));
  ShowMessage('F : '+IntToStr(F));
end;

Show full unit code

  A : 32
  B : 100
  C : -12
  D : 30
  E : -30
  F : 120

Example code : Catching string to integer conversion errors

var
  A : Integer;

begin
  // We will catch conversion errors
  try
    A := StrToInt('100 ');    // Trailing blanks are not supported
  except
    on Exception : EConvertError do
      ShowMessage(Exception.Message);
  end;

  try
    A := StrToInt('$FG');    // 'G' is an invalid hexadecimal digit
  except
    on Exception : EConvertError do
      ShowMessage(Exception.Message);
  end;
end;

Show full unit code

'100 ' is not a valid integer value
'$FG' is not a valid integer value