What is the C function to raise a number to a power

Question

How do I raise a number to a power   2 1  2 2  2 3   etc

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I am using the library cmath or math h in order to make use of the pow   library functions that takes care of the powers   include lt iostream gt   include lt cmath gt   int main         double number power  result      cout lt  lt   nEnter the number to raise to power         cin gt  gt number      cout lt  lt   nEnter the power to raise to         cin gt  gt power       result   pow number power        cout lt  lt   n  lt  lt  number  lt  lt     lt  lt  power lt  lt       lt  lt  result       return 0

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Many answers have suggested pow   or similar alternatives or their own implementations  However  given the examples  2 1  2 2 and 2 3  in your question  I would guess whether you only need to raise 2 to an integer power  If this is the case  I would suggest you to use 1  lt  lt  n for 2 n

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use pow   function in cmath  tgmath or math h library    include  lt iostream gt   include  lt cmath gt  using namespace std   int main     int a b  cin  gt  gt  a  gt  gt  b  cout  lt  lt  pow a b   lt  lt  endl     this calculates a b  return 0      do note that if you give input to power as any data type other than long double then the answer will be promoted to that of double  that is it will take input and give output as double  for long double inputs the return type is long double  for changing the answer to int use      int c  int pow a b   But  do keep in mind for some numbers this may result in a number less than the correct answer  so for example you have to calculate 5 2  then the answer can be returned as 24 99999999999 on some compilers  on changing the data type to int the answer will be 24 rather than 25 the correct answer  So  do this  int c  int  pow a b  0 5    Now  your answer will be correct  also  for very large numbers data is lost in changing data type double to long long int  for example you write  long long int c  long long int  pow a b  0 5     and give input a 3 and b 38 then the result will come out to be 1350851717672992000 while the correct answer is 1350851717672992089  this happens because pow   function return 1 35085e 18 which gets promoted to int as 1350851717672992000  I suggest writing a custom power function for such scenarios  like -  long long int   pow  long long int a  long long int b    long long int q 1  for  long long int i 0 i lt  b-1 i      q q a     return q      and then calling it whenever you want like    int main     long long int a b  cin  gt  gt  a  gt  gt  b   long long int c   pow a b   cout  lt  lt  c  lt  lt  endl   return 0      For numbers greater than the range of long long int  either use boost library or strings

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include  lt iostream gt   include  lt conio h gt   using namespace std   double raiseToPow double  int    raiseToPow variable of type double which takes arguments  double  int   void main         double x    initializing the variable x and i      int i      cout lt  lt  please enter the number        cin gt  gt x      cout lt  lt  plese enter the integer power that you want this number raised to       cin gt  gt i      cout lt  lt x lt  lt  raise to power  lt  lt i lt  lt  is equal to  lt  lt raiseToPow x i         definition of the function raiseToPower  double raiseToPow double x  int power        double result      int i      result  1 0      for  i 1  i lt  power i                  result   result x            return result

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int power  int i  int ow     works only for ow  gt   1      but does not require  lt cmath gt  library        if  ow  gt  1                 i   i   power  i  ow - 1             return i     cout  lt  lt  power 6 7     you can enter variables here

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In C   the      operator is a bitwise OR   It does not work for raising to a power   The x  lt  lt  n is a left shift of the binary number which is the same as multiplying x by 2 n number of times and that can only be used when raising 2 to a power   The POW function is a math function that will work generically

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std  pow in the  lt cmath gt  header has these overloads   pow float  float   pow float  int   pow double  double      taken over from C pow double  int   pow long double  long double   pow long double  int     Now you can t just do   pow 2  N    with N being an int  because it doesn t know which of float  double  or long double version it should take  and you would get an ambiguity error  All three would need a conversion from int to floating point  and all three are equally costly    Therefore  be sure to have the first argument typed so it matches one of those three perfectly  I usually use double  pow 2 0  N    Some lawyer crap from me again  I ve often fallen in this pitfall myself  so I m going to warn you about it

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You should be able to use normal C methods in math    include  lt cmath gt   pow 2 3   if you re on a unix-like system  man cmath  Is that what you re asking   Sujal

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Note that the use of pow x y  is less efficient than x x x y times as shown and answered here https   stackoverflow com a 2940800 319728   So if you re going for efficiency use x x x

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Use the pow x y  function  See Here  Just include math h and you re all set

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First add  include  lt cmath gt  then you can use pow methode in your code for example    pow 3 5  3     Which 3 5 is base and 3 is exp

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It s pow or powf in  lt math h gt   There is no special infix operator like in Visual Basic or Python

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pow 2 0 1 0  pow 2 0 2 0  pow 2 0 3 0    Your original question title is misleading  To just square  use 2 2

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if you want to deal with base 2 only then i recommend using left shift operator  lt  lt  instead of math library   sample code    int exp   16  for int base 2   1  base 2  lt   1  lt  lt  exp    base 2  lt  lt   1    std  cout  lt  lt  base 2  lt  lt  std  endl      sample output     1   2   4   8   16  32  64  128  256  512  1024  2048  4096  8192  16384  32768

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While pow  base  exp   is a great suggestion  be aware that it typically works in floating-point   This may or may not be what you want  on some systems a simple loop multiplying on an accumulator will be faster for integer types   And for square specifically  you might as well just multiply the numbers together yourself  floating-point or integer  it s not really a decrease in readability  IMHO  and you avoid the performance overhead of a function call

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I don t have enough reputation to comment  but if you like working with QT  they have their own version        include  lt QtCore qmath h gt      qPow x  y      returns x raised to the y power    Or if you aren t using QT  cmath has basically the same thing        include  lt cmath gt      double x   5  y   7    As an example  5   7   78125     pow x  y     Should return this  78125

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pow   in the cmath library  More info here  Don t forget to put  include lt cmath gt  at the top of the file

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