请问用C语言怎么可以实现对数和指数运算？

请问用C语言怎么可以实现对数和指数运算？最好能有例程给我看看。谢谢！

//////////////////////////////////////////////////////////////////////
//
// 对数的例子//
// <filename> : main.cpp
//
// Functions:
//
// exp, log, log10
//////////////////////////////////////////////////////////////////////

#include <iostream> // for i/o functions
#include <valarray> // for valarray
#include <math.h> // for exp(), log(), and log10()

using namespace std;

#define ARRAY_SIZE 3 // array size

typedef valarray<double> DB_VARRAY;

void main()
{
// Set val_array to contain values 1, 10, 100 for the following test.
DB_VARRAY val_array(ARRAY_SIZE);
for (int i = 0; i < ARRAY_SIZE; i++)
val_array[i] = pow(10, i);

// Display the size of val_array.
cout << "Size of val_array = " << val_array.size() << "\r\n";

// Display the content of val_array before calling exp, log, and
// log10 functions.
cout << "The values in val_array:\r\n";
for (i = 0; i < ARRAY_SIZE; i++)
cout << val_array[i] << " ";
cout << "\r\n\r\n";

// rvalue_array to hold the return value from calling the sqrt() and
// pow() functions.
DB_VARRAY rvalue_array;

// ----------------------------------------------------------------
// exp() - display the content of rvalue_array
// ----------------------------------------------------------------
rvalue_array = exp(val_array);
cout << "The result after calling exp():\r\n";
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << "\r\n\r\n";

// ----------------------------------------------------------------
// log() - display the content of rvalue_array
// ----------------------------------------------------------------
rvalue_array = log(val_array);
cout << "The result after calling log():\r\n";
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << "\r\n\r\n";

// ----------------------------------------------------------------
// log10() - display the content of rvalue_array
// ----------------------------------------------------------------
rvalue_array = log10(val_array);
cout << "The result after calling log10():\r\n";
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << "\r\n\r\n";
}

Program Output is:

Size of val_array = 3

The values in val_array:

1 10 100

The result after calling exp():

2.71828 22026.5 2.68812e+043

The result after calling log():

0 2.30259 4.60517

The result after calling log10():

0 1 2

//////////////////////////////////////////////////////////////////////
//
// 指数的例子//
// main.cpp : Illustrates the use of STL sqrt() and pow() functions.
//
// Functions:
//
// sqrt, pow
//////////////////////////////////////////////////////////////////////

#include <iostream> // for i/o functions
#include <valarray> // for valarray
#include <cmath> // for sqrt() and pow()

using namespace std ;

#define ARRAY_SIZE 3 // array size

void main()
{
// Set val_array to contain values 1, 4, 9 for the following test
valarray<double> val_array(ARRAY_SIZE);

for (int i = 0; i < ARRAY_SIZE; i++)
val_array[i] = (i+1) * (i+1);

// Display the size of val_array
cout << "Size of val_array = " << val_array.size() << endl;

// Display the values of val_array before calling sqrt() and pow().
cout << "The values in val_array:" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << val_array[i] << " ";
cout << endl << endl;

// Initialize rev_valarray that is the reverse of val_array.
valarray<double> rev_valarray(ARRAY_SIZE);
for (i = 0; i < ARRAY_SIZE; i++)
rev_valarray[i] = val_array[ARRAY_SIZE - i - 1];

// Display the size of rev_valarray.
cout << "Size of rev_valarray = " << rev_valarray.size() << endl;

// Display the values of rev_valarray.
cout << "The values in rev_valarray:" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rev_valarray[i] << " ";
cout << endl << endl;

// rvalue_array to hold the return value from calling the sqrt() and
// pow() functions.
valarray<double> rvalue_array;

// ----------------------------------------------------------------
// sqrt() - display the content of rvalue_array
// ----------------------------------------------------------------

// Display the result of val_array after calling sqrt().
rvalue_array = sqrt(val_array);
cout << "The result of val_array after calling sqrt():" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << endl << endl;

// ----------------------------------------------------------------
// pow() - display the content of rvalue_array
// ----------------------------------------------------------------

// This template function returns an object of class valarray<T>,
// each of whose elements at I is x[I] raised to the power of y[I].
rvalue_array = pow(val_array, rev_valarray);
cout << "The result after calling pow(val_array, rev_valarray):"
<< endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << endl << endl;

// This template function stores in element I x[I] raised to the
// power of y, where y=2.0.
rvalue_array = pow(val_array, 2.0);
cout << "The result after calling pow(val_array, 2.0):" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << endl << endl;

// This template function stores in element I x raised to the
// y[I] power, where x=2.0.
rvalue_array = pow(2.0, val_array);
cout << "The result after calling pow(2.0, val_array):" << endl;
for (i = 0; i < ARRAY_SIZE; i++)
cout << rvalue_array[i] << " ";
cout << endl << endl;
}

Program Output is:

Size of val_array = 3
The values in val_array:
1 4 9

Size of rev_valarray = 3
The values in rev_valarray:
9 4 1

The result of val_array after calling sqrt():
1 2 3

The result after calling pow(val_array, rev_valarray):
1 256 9

The result after calling pow(val_array, 2.0):
1 16 81

The result after calling pow(2.0, val_array):
2 16 512

以上例子全是MSDN的标准例子 , 安装MSDN吧, 这种问题迎刃而解

参考资料：MSDN

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