DelphiBasics
 StrToInt64DefFunction Convert a string into an Int64 value with default SysUtils unit
 function StrToInt64Def(const IntegerString string; Default Integer):Int64;
Description
The StrToInt64Def function converts an Integer string, IntegerString such as '123' into an Int64 value, with a Default if the conversion fails.

It supports +ve and -ve numbers, and hexadecimal numbers, as prefixed by \$ or 0x.
Notes
No conversion errors are generated - bad conversions simply result in the Default being returned.
Related commands
 Int64 A 64 bit sized integer - the largest in Delphi IntToStr Convert an integer into a string StrToInt Convert an integer string into an Integer value StrToInt64 Convert an integer string into an Int64 value StrToIntDef Convert a string into an Integer value with default

Example code : Converting decimal and hexadecimal numbers
var
A, B, C, D, E, F : Int64;

begin
A := 32;
B := StrToInt64Def('100', 0);    // '100' string converted to 100 integer
C := StrToInt64Def('  -12', 0);  // Leading blanks are ignored
E := StrToInt64Def('-0x1E', 0);  // ... 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 : Int64; begin   // No need to catch conversion errors   A := StrToInt64Def('100 ', 55);    // Trailing blanks are not supported   ShowMessage('Value = '+IntToStr(A));   A := StrToInt64Def('\$FG' , 66);    // 'G' is an invalid hexadecimal digit   ShowMessage('Value = '+IntToStr(A)); end; Show full unit code Value = 55   Value = 66