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Integer and floating point numbers
The different number types in Delphi
Delphi provides many different data types for storing numbers. Your choice depends on the data you want to handle. In general, smaller number capacities mean smaller variable sizes, and faster calculations. Ideally, you should use a type that comfortably copes with all possible values of the data it will store.

For example, a Byte type can comfortably hold the age of a person - no-one to date has lived as long as 255 years.

With decimal numbers, the smaller capacity types also have less precision. Less numbers of significant digits. Let us look at the different types:

 ` Type  Storage size                        Range              Byte       1                             0 to 255 ShortInt   1                          -127 to 127 Word       2                             0 to 65,535 SmallInt   2                       -32,768 to 32,767 LongWord   4                             0 to 4,294,967,295 Cardinal   4*                            0 to 4,294,967,295 LongInt    4                -2,147,483,648 to 2,147,483,647 Integer    4*               -2,147,483,648 to 2,147,483,647 Int64      8    -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807  Single     4     7  significant digits, exponent   -38 to +38 Currency   8    50+ significant digits, fixed 4 decimal places Double     8    15  significant digits, exponent  -308 to +308 Extended  10    19  significant digits, exponent -4932 to +4932  * Note : the Integer and Cardinal types are both 4 bytes in size at present (Delphi release 7), but are not guaranteed to be this size in the future. All other type sizes are guaranteed.`

Assigning to and from number variables
Number variables can be assigned from constants, other numeric variables, and expressions:

 ` const   YOUNG_AGE = 23;         // Small integer constant   MANY      = 300;        // Bigger integer constant   RICH      = 100000.00;  // Decimal number : note no thousand commas  var   Age       : Byte;       // Smallest positive integer type   Books     : SmallInt;   // Bigger signed integer   Salary    : Currency;   // Decimal used to hold financial amounts   Expenses  : Currency;   TakeHome  : Currency;  begin   Age       := YOUNG_AGE; // Assign from a predefined constant   Books     := MANY + 45; // Assign from a mix of constants (expression)   Salary    := RICH;      // Assign from a predefined constant   Expenses  := 12345.67;  // Assign from a literal constant   TakeHome  := Salary;    // Assign from another variable   TakeHome  := TakeHome - Expenses;  // Assign from an expression end;`

 ` Age       is set to 23 Books     is set to 345 Salary    is set to 100000.00 Expenses  is set to 12345.67 TakeHome  is set to 87654.33`

Numerical operators
Number calculations, or expressions, have a number of primitive operators available:

 ` +   : Add one number to another -   : Subtract one number from another *   : Multiply two numbers /   : Divide one decimal number by another div : Divide one integer number by another mod : Remainder from dividing one integer by another`

When using these multiple operators in one expression, you should use round brackets to wrap around sub-expressions to ensure that the result is obtained. This is illustrated in the examples below:

 ` var   myInt : Integer;  // Define integer and decimal variables   myDec : Single;  begin   myInt := 20;           // myInt is now 20   myInt := myInt + 10;   // myInt is now 30   myInt := myInt - 5;    // myInt is now 25   myInt := myInt * 4;    // myInt is now 100   myInt := 14 div 3;     // myInt is now 4   (14 / 3 = 4 remainder 2)   myInt := 14 mod 3;     // myInt is now 2   (14 / 3 = 4 remainder 2)     myInt := 12 * 3 - 4;   // myInt is now 32  (* comes before -)   myInt := 12 * (3 - 4); // myInt is now -12 (brackets come before *)    myDec := 2.222 / 2.0;  // myDec is now 1.111 end;`

Numeric functions and procedures
Delphi provides many builtin functions and procedures that can perform numeric calculations. Some examples are given below - click on any to discover more. Note that these routines are stored in Units that are shipped with Delphi, and which form part of the standard delphi Run Time Library. You will need to include a reference to the Unit in order to use it (the code example provided with each gives the unit name and shows how to refer to it).

 ` Abs  Returns the absolute value of a signed number Max  Gives the maximum of two integer values Min  Gives the minimum of two integer values Mean Gives the average of a set of numbers Sqr  Gives the square of a number Sqrt Gives the square root of a number Exp  Gives the exponent of a number Shl  Shifts the bits in a number left Shr  Shifts the bits in a number right Tan  Gives the Tangent of a number Cos  Gives the Cosine of a number Sin  Gives the Sine of a number`

Converting from numbers to strings
Delphi also provides routines that convert numbers into strings. This is often useful for display purposes.

 ` Str       Converts a number to a string in a simple manner CurrToStr Converts a Currency variable to a string Format    Number to string conversion with formatting IntToStr  Converts an integer to a string IntToHex  Converts a number into a hexadecimal string`

Converting from strings to numbers
Finally, Delphi provides string to number conversion utilities. Here are some examples:

 ` StrToInt     Converts an integer string into an integer StrToIntDef  Fault tolerant version of StrToInt StrToFloat   Converts a decimal string to a number`

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