how do I initialize a float to its max min value

Question

How do I hard code an absolute maximum or minimum value for a float or double  I want to search out the max min of an array by simply iterating through and catching the largest   There are also positive and negative infinity for floats  should I use those instead  If so  how do I denote that in my code

User · Answer

May I suggest that you initialize your  max and min so far  variables not to infinity  but to the first number in the array

User · Answer

You can either use -FLT MAX  or -DBL MAX  for the maximum magnitude negative number and FLT MAX  or DBL MAX  for positive  This gives you the range of possible float  or double  values   You probably don t want to use FLT MIN  it corresponds to the smallest magnitude positive number that can be represented with a float  not the most negative value representable with a float   FLT MIN and FLT MAX correspond to std  numeric limits lt float gt   min   and std  numeric limits lt float gt   max

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To manually find the minimum of an array you don t need to know the minimum value of float   float myFloats        float minimum   myFloats 0   for  int i   0  i  lt  myFloatsSize    i      if  myFloats i   lt  minimum          minimum   myFloats i           And similar code for the maximum value

User · Answer

You can use std  numeric limits which is defined in  lt limits gt  to  find the minimum or maximum value of types  As long as a specialization exists for the type   You can also use it to retrieve infinity  and put a - in front for negative infinity     include  lt limits gt          std  numeric limits lt float gt   max    std  numeric limits lt float gt   min    std  numeric limits lt float gt   infinity      As noted in the comments  min   returns the lowest possible positive value  In other words the positive value closest to 0 that can be represented  The lowest possible value is the negative of the maximum possible value   There is of course the std  max element and min element functions  defined in  lt algorithm gt   which may be a better choice for finding the largest or smallest value in an array

User · Answer

There s no real need to initialize to smallest largest possible to find the smallest largest in the array   double largest   smallest   array 0   for  int i 1  i lt array size  i          if  array i   lt  smallest          smallest   array i       if  array i   gt  largest0         largest  array i       Or  if you re doing it more than once    include  lt utility gt   template  lt class iter gt  std  pair lt typename iter  value type  typename iter  value type gt  find extrema iter begin  iter end        std  pair lt typename iter  value type  typename iter  value type gt  ret      ret first   ret second    begin      while    begin    end            if   begin  lt  ret first             ret first    begin          if   begin  gt  ret second             ret second    begin          return ret      The disadvantage of providing sample code -- I see others have already suggested the same idea   Note that while the standard has a min element and max element  using these would require scanning through the data twice  which could be a problem if the array is large at all  Recent standards have addressed this by adding a std  minmax element  which does the same as the find extrema above  find both the minimum and maximum elements in a collection in a single pass    Edit  Addressing the problem of finding the smallest non-zero value in an array of unsigned  observe that unsigned values  wrap around  when they reach an extreme  To find the smallest non-zero value  we can subtract one from each for the comparison  Any zero values will  wrap around  to the largest possible value for the type  but the relationship between other values will be retained  After we re done  we obviously add one back to the value we found   unsigned int min nonzero std  vector lt unsigned int gt  const  amp values         if  vector size      0          return 0      unsigned int temp   values 0 -1      for  int i 1  i lt values size    i            if  values i -1  lt  temp              temp   values i -1      return temp 1      Note this still uses the first element for the initial value  but we still don t need any  special case  code -- since that will wrap around to the largest possible value  any non-zero value will compare as being smaller  The result will be the smallest nonzero value  or 0 if and only if the vector contained no non-zero values

[c++] how do I initialize a float to its max/min value?

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