C++ log10()用法及代碼示例

C++ log10() 函數

log10() 函數是 cmath 頭文件的庫函數，用於獲取給定值的常用對數(以 10 為底的對數)。它接受一個值 (float，double， 或者long double) 並返回常用對數。

log10() 函數的語法：

C++11：

     double log10 (double x);
      float log10 (float x);
long double log10 (long double x);
     double log10 (T x);

參數：

• x– 表示要找到其常用對數的值。

返回值：

它返回給定值的常用對數x。

注意：

• 如果給定的值為負，則會導致域錯誤。
• 如果給定值為零，則可能會導致極點錯誤。

例：

    Input:
    float x = 10.0f
    
    Function call:
    log(x);
    
    Output:
    1

演示log10()函數示例的C++代碼

// C++ code to demonstrate the example of
// log10() function

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    float x = 0.0f;

    x = 10.0f;
    cout << "log10(" << x << "):" << log10(x) << endl;

    x = 1.0f;
    cout << "log10(" << x << "):" << log10(x) << endl;

    x = 20.0f;
    cout << "log10(" << x << "):" << log10(x) << endl;

    x = -10.4f;
    cout << "log10(" << x << "):" << log10(x) << endl;

    x = 0.0f;
    cout << "log10(" << x << "):" << log10(x) << endl;

    x = 100.6f;
    cout << "log10(" << x << "):" << log10(x) << endl;

    return 0;
}

輸出

log10(10):1
log10(1):0
log10(20):1.30103
log10(-10.4):nan
log10(0):-inf
log10(100.6):2.0026

參考：C++ log10() 函數