Overview:  the Math Library and the Character Type Library

Selected constants and function declarations from "cmath" ("math.h"):

  #define M_E            2.7182818284590452354
  #define M_LOG2E        1.4426950408889634074
  #define M_LOG10E       0.43429448190325182765
  #define M_LN2          0.69314718055994530942
  #define M_LN10         2.30258509299404568402
  #define M_PI           3.14159265358979323846
  #define M_PI_2         1.57079632679489661923
  #define M_PI_4         0.78539816339744830962
  #define M_1_PI         0.31830988618379067154
  #define M_2_PI         0.63661977236758134308
  #define M_2_SQRTPI     1.12837916709551257390
  #define M_SQRT2        1.41421356237309504880
  #define M_SQRT1_2      0.70710678118654752440

  double cos( double );
  double sin( double );
  double tan( double );
 
  double acos( double );
  double asin( double );
  double atan( double );
 
  double cosh( double );
  double sinh( double );
  double tanh( double );
 
  double exp( double );
  double log( double );
  double log10( double );
 
  double pow( double, double );
  double sqrt( double );
 
  double ceil( double );
  double fabs( double );
  double floor( double );
 
Selected function declarations from "cctype" ("ctype.h"):

  int isalnum( int );
  int isalpha( int );
  int iscntrl( int );
  int isdigit( int );
  int isgraph( int );
  int islower( int );
  int isprint( int );
  int ispunct( int );
  int isspace( int );
  int isupper( int );
  int isxdigit( int );
 
  int tolower( int );
  int toupper( int );