DelphiBasics
 StrToInt64Function Convert an integer string into an Int64 value SysUtils unit
 function StrToInt64(IntegerString string):Int64;
Description
The StrToInt64 function converts an Integer string, IntegerString such as '123' into an Int64 return value.

It supports +ve and -ve numbers, and hexadecimal numbers, as prefixed by \$ or 0x.
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
 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 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 : Int64;

begin
A := 32;
B := StrToInt64('100');    // '100' string converted to 100 integer
C := StrToInt64('  -12');  // Leading blanks are ignored
D := StrToInt64('\$1E');    // Hexadecimal values start with a '\$'
E := StrToInt64('-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 : Int64; begin   // We will catch conversion errors   try     A := StrToInt64('100 ');    // Trailing blanks are not supported   except     on Exception : EConvertError do       ShowMessage(Exception.Message);   end;   try     A := StrToInt64('\$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