C++ STL之 #include $头文件$

#include <stdio.h>      
#include <math.h>       

#define PI 3.14159265

int main ()
{
  double degrees, cos_result, sin_result, tan_result;
  degrees = 60.0;
  cos_result = cos ( degrees * PI / 180.0 );
  sin_result = sin ( degrees * PI / 180.0 );
  tan_result = tan ( degrees * PI / 180.0 );
  printf ("The cosine of %.1f degrees is %f.\n", degrees, cos_result );
  printf ("The sine of %.1f degrees is %f.\n", degrees, sin_result );
  printf ("The tangent of %.1f degrees is %f.\n", degrees, tan_result );
  return 0;
}

执行结果：
The cosine of 60.0 degrees is 0.500000.
The sine of 60.0 degrees is 0.866025.
The tangent of 60.0 degrees is 1.732051.

#include <stdio.h>      
#include <math.h>      

#define PI 3.14159265

int main ()
{
  double value, acos_result, asin_result, atan_result;
  value = 0.5;
  acos_result = acos (value) * 180.0 / PI;
  asin_result = asin (value) * 180.0 / PI;
  atan_result = atan (value) * 180.0 / PI;
  printf ("The arc cosine of %.1f is %.1f degrees.\n", value, acos_result);
  printf ("The arc sine of %.1f is %.1f degrees.\n", value, asin_result);
  printf ("The arc tangent of %.1f is %.1f degrees.\n", value, atan_result);
  return 0;
}

执行结果：
The arc cosine of 0.5 is 60.0 degrees.
The arc sine of 0.5 is 30.0 degrees.
The arc tangent of 0.5 is 26.6 degrees.

#include <stdio.h>      
#include <math.h>       

int main ()
{
  double param, exp_result, exp2_result;
  param = 5.0;
  exp_result = exp (param);
  exp2_result = exp2 (param);
  printf ("The exponential value of %.1f is %.1f.\n", param, exp_result );
  printf ("2 ^ %.1f = %.1f.\n", param, exp2_result );
  return 0;
}

执行结果：
The exponential value of 5.0 is 148.4.
2 ^ 5.0 = 32.0.

#include <stdio.h>      
#include <math.h>       

int main ()
{
  double param, log_result, log2_result, logb_result, log10_result;
  param = 8;
  log_result = log (param);
  log2_result = log2 (param);
  logb_result = logb (param);
  log10_result = log10(param);
  printf ("log(%f) = %f\n", param, log_result);
  printf ("log2(%f) = %f.\n", param, log2_result);
  printf ("logb(%f) = %f.\n", param, logb_result );
  printf ("log10(%f) = %f.\n", param, log10_result);
  return 0;
}

执行结果：
log(8.000000) = 2.079442
log2(8.000000) = 3.000000.
logb(8.000000) = 3.000000.
log10(8.000000) = 0.903090.

#include <stdio.h>      /* printf */
#include <math.h>       /* pow */

int main ()
{
  double param, result;
  param = 1024.0;
  result = sqrt (param);
  printf ("sqrt(%f) = %f\n", param, result );
  printf ("7 ^ 3 = %f\n", pow (7.0, 3.0) );
  return 0;
}

执行结果：
sqrt(1024.000000) = 32.000000
7 ^ 3 = 343.000000

#include <stdio.h>      
#include <math.h>       

int main ()
{
  printf ( "ceil的功能是上取\n" );
  printf ( "ceil of 2.3 is %.1f\n", ceil(2.3) );
  printf ( "ceil of 3.8 is %.1f\n", ceil(3.8) );
  printf ( "ceil of -2.3 is %.1f\n", ceil(-2.3) );
  printf ( "ceil of -3.8 is %.1f\n", ceil(-3.8) );
  printf ( "floor的功能是下取\n" );
  printf ( "floor of 2.3 is %.1lf\n", floor (2.3) );
  printf ( "floor of 3.8 is %.1lf\n", floor (3.8) );
  printf ( "floor of -2.3 is %.1lf\n", floor (-2.3) );
  printf ( "floor of -3.8 is %.1lf\n", floor (-3.8) );
  printf ( "round 的功能四舍五入\n" );
  printf ( "round of 2.3 is %.1lf\n", round (2.3) );
  printf ( "round of 3.8 is %.1lf\n", round (3.8) );
  printf ( "round of -2.3 is %.1lf\n", round (-2.3) );
  printf ( "round of -3.8 is %.1lf\n", round (-3.8) );
  printf ( "fmod 的功能浮点数取模\n" );
  printf ( "fmod of 5.3 / 2 is %f\n", fmod (5.3,2) );
  printf ( "fmod of 18.5 / 4.2 is %f\n", fmod (18.5,4.2) );
  return 0;
}

执行结果：
ceil的功能是上取
ceil of 2.3 is 3.0
ceil of 3.8 is 4.0
ceil of -2.3 is -2.0
ceil of -3.8 is -3.0
floor的功能是下取
floor of 2.3 is 2.0
floor of 3.8 is 3.0
floor of -2.3 is -3.0
floor of -3.8 is -4.0
round 的功能四舍五入
round of 2.3 is 2.0
round of 3.8 is 4.0
round of -2.3 is -2.0
round of -3.8 is -4.0
fmod 的功能浮点数取模
fmod of 5.3 / 2 is 1.300000
fmod of 18.5 / 4.2 is 1.700000

#include <stdio.h>      
#include <math.h>       

int main ()
{
  printf ("fmin (100.0, 1.0) = %f\n", fmin(100.0,1.0));
  printf ("fmin (-100.0, 1.0) = %f\n", fmin(-100.0,1.0));
  printf ("fmin (-100.0, -1.0) = %f\n", fmin(-100.0,-1.0));
  printf ("fmax (100.0, 1.0) = %f\n", fmax(100.0,1.0));
  printf ("fmax (-100.0, 1.0) = %f\n", fmax(-100.0,1.0));
  printf ("fmax (-100.0, -1.0) = %f\n", fmax(-100.0,-1.0));
  return 0;
}

执行结果：
fmin (100.0, 1.0) = 1.000000
fmin (-100.0, 1.0) = -100.000000
fmin (-100.0, -1.0) = -100.000000
fmax (100.0, 1.0) = 100.000000
fmax (-100.0, 1.0) = 1.000000
fmax (-100.0, -1.0) = -1.000000

#include <stdio.h>   
#include <math.h>   
#include <cmath>

int main ()
{
  printf ("The absolute value of 3.1416 is %f\n", fabs (3.1416) );
  printf ("The absolute value of -10.6 is %f\n", fabs (-10.6) );
  printf ("The absolute value of 3.1416 is %f\n", std::abs (3.1416) );
  printf ("The absolute value of -10.6 is %f\n", std::abs (-10.6) );
  return 0;
}

执行结果：
The absolute value of 3.1416 is 3.141600
The absolute value of -10.6 is 10.600000
The absolute value of 3.1416 is 3.141600
The absolute value of -10.6 is 10.600000