Difference between Math Floor and Math Truncate

Question

What is the difference between Math Floor   and Math Truncate   in  NET

User · Answer

They are functionally equivalent with positive numbers. The difference is in how they handle negative numbers.

For example:

Math.Floor(2.5) = 2
Math.Truncate(2.5) = 2

Math.Floor(-2.5) = -3
Math.Truncate(-2.5) = -2

MSDN links: - Math.Floor Method - Math.Truncate Method

P.S. Beware of Math.Round it may not be what you expect.

To get the "standard" rounding result use:

float myFloat = 4.5;
Console.WriteLine( Math.Round(myFloat) ); // writes 4
Console.WriteLine( Math.Round(myFloat, 0, MidpointRounding.AwayFromZero) ) //writes 5
Console.WriteLine( myFloat.ToString("F0") ); // writes 5

User · Answer

Math Floor    Returns the largest integer less than or equal to the specified double-precision floating-point number   Math Round    Rounds a value to the nearest integer or to the specified number of fractional digits

User · Answer

Truncate drops the decimal point

User · Answer

Follow these links for the MSDN descriptions of    Math Floor  which rounds down towards negative infinity  Math Ceiling  which rounds up towards positive infinity  Math Truncate  which rounds up or down towards zero  Math Round  which rounds to the nearest integer or specified number of decimal places  You can specify the behavior if it s exactly equidistant between two possibilities  such as rounding so that the final digit is even   Round 2 5 MidpointRounding ToEven   becoming 2  or so that it s further away from zero   Round 2 5 MidpointRounding AwayFromZero   becoming 3     The following diagram and table may help   -3        -2        -1         0         1         2         3   -- ------ --------- ---- ---- -- ------ ---- ---- ------- -      a                     b       c           d            e                         a -2 7  b -0 5  c 0 3  d 1 5  e 2 8                                                            Floor                    -3      -1      0      1      2 Ceiling                  -2       0      1      2      3 Truncate                 -2       0      0      1      2 Round  ToEven            -3       0      0      2      3 Round  AwayFromZero      -3      -1      0      2      3   Note that Round is a lot more powerful than it seems  simply because it can round to a specific number of decimal places  All the others round to zero decimals always  For example   n   3 145  a   System Math Round  n  2  MidpointRounding ToEven            3 14 b   System Math Round  n  2  MidpointRounding AwayFromZero      3 15   With the other functions  you have to use multiply divide trickery to achieve the same effect   c   System Math Truncate  n   100    100                        3 14 d   System Math Ceiling  n   100    100                         3 15

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Try this  Examples    Math Floor   vs  Math Truncate    Math Floor 2 56    2 Math Floor 3 22    3 Math Floor -2 56    -3 Math Floor -3 26    -4  Math Truncate 2 56    2 Math Truncate 2 00    2 Math Truncate 1 20    1 Math Truncate -3 26    -3 Math Truncate -3 96    -3   Also Math Round       Math Round 1 6    2    Math Round -8 56    -9    Math Round 8 16    8    Math Round 8 50    8    Math Round 8 51    9   math floor    Returns the largest integer less than or equal to the specified number  MSDN system math floor  math truncate    Calculates the integral part of a number  MSDN system math truncate

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Some examples   Round 1 5    2 Round 2 5    2 Round 1 5  MidpointRounding AwayFromZero    2 Round 2 5  MidpointRounding AwayFromZero    3 Round 1 55  1    1 6 Round 1 65  1    1 6 Round 1 55  1  MidpointRounding AwayFromZero    1 6 Round 1 65  1  MidpointRounding AwayFromZero    1 7  Truncate 2 10    2 Truncate 2 00    2 Truncate 1 90    1 Truncate 1 80    1

User · Answer

Math floor   will always round down ie   it returns LESSER integer  While round   will return the NEAREST integer  math floor    Returns the largest integer less than or equal to the specified number   math truncate    Calculates the integral part of a number

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Going by the Mathematical Definition of Floor  that is   quot Greatest integer less than or equal to a number quot   This is completely unambiguous  whereas  Truncate just removes the fractional part  which is equivalent to round towards 0

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Math Floor   rounds toward negative infinity   Math Truncate rounds up or down towards zero   For example   Math Floor -3 4        -4 Math Truncate -3 4     -3   while   Math Floor 3 4        3 Math Truncate 3 4     3

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Math Floor rounds down  Math Ceiling rounds up  and Math Truncate rounds towards zero  Thus  Math Truncate is like Math Floor for positive numbers  and like Math Ceiling for negative numbers  Here s the reference   For completeness  Math Round rounds to the nearest integer  If the number is exactly midway between two integers  then it rounds towards the even one  Reference   See also  Pax Diablo s answer  Highly recommended

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Math Floor     It gives the largest integer less than or equal to the given number      Math Floor 3 45   3     Math Floor -3 45   -4  Math Truncate    It removes the decimal places of the number and replace with zero Math Truncate 3 45  3  Math Truncate -3 45  -3  Also from above examples we can see that floor and truncate are same for positive numbers

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Math Floor   rounds   toward negative infinity  in compliance to IEEE Standard 754 section 4   Math Truncate   rounds   to the nearest integer towards zero

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Math floor sliiiide to the left    Math ceil sliiiide to the right    Math truncate criiiiss crooooss  floor ceil always towards 0  Math round cha cha  real smooth     go to closest side  Let s go to work          To the left    Math floor Take it back now y all    -- Two hops this time    - 2 Everybody clap your hands    How low can you go  Can you go down low  All the way to the floor  if  this     quot wrong quot       return  quot i don t wanna be right quot    Math truncate x  is also the same as int x   by removing a positive or negative fraction  you re always heading towards 0

[.net] Difference between Math.Floor() and Math.Truncate()

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