# C log() function

## C log() function - Calculate natural logarithm

**Syntax:**

double log(double x)

The log() function is used to calculate the natural logarithm (base e) of x.

**Parameters:**

Name | Description | Required /Optional |
---|---|---|

x | Value whose logarithm is to be found. | Required |

**Return value from log()**

- Upon successful completion, the function returns the natural logarithm of x.

**Example: log() function**

The following example shows the usage of log() function.

```
#include <math.h>
#include <stdio.h>
int main(void)
{
double x = 1.0, y;
y = log(x);
printf("The natural logarithm of %lf is %lf\n", x, y);
x = 10.0;
y = log(x);
printf("The natural logarithm of %lf is %lf\n", x, y);
x = 1000.0;
y = log(x);
printf("The natural logarithm of %lf is %lf\n", x, y);
}
```

Output:

The natural logarithm of 1.000000 is 0.000000 The natural logarithm of 10.000000 is 2.302585 The natural logarithm of 1000.000000 is 6.907755

**C Programming Code Editor:**

**Previous C Programming:** C ldexp()

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## C Programming: Tips of the Day

**What's the point of const pointers?**

const is a tool which you should use in pursuit of a very important C++ concept:

Find bugs at compile-time, rather than run-time, by getting the compiler to enforce what you mean.

Even though it does not change the functionality, adding const generates a compiler error when you're doing things you didn't mean to do. Imagine the following typo:

void foo(int* ptr) { ptr = 0;// oops, I meant *ptr = 0 }

If you use int* const, this would generate a compiler error because you're changing the value to ptr. Adding restrictions via syntax is a good thing in general. Just don't take it too far -- the example you gave is a case where most people don't bother using const.

Ref : https://bit.ly/33Cdn3Q

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