What is infinity in C?

There is no representation of infinity in C. jlliagre pointed out the max value for signed integers. There ones for unsigned long int, double, float, etc. Consider reading the limits.h file in your /usr/include directory.

Does C have NaN?

C does not require, when a is a not-a-number, for a == NAN to return false. IEEE requires it. Even implementations that adhere to IEEE, do so mostly. When isnan() not implemented, still better to wrap the test than directly code a == NAN .

Is there infinity in C++?

isinf() function in C++ The isinf() function is use to determine whether the given number is infinity or not i.e positive infinity or negative infinity both. This function returns 1 if the given number is infinite otherwise this function returns zero.

How does NaN work in C?

NaN is unordered: it is not equal to, greater than, or less than anything, including itself. x == x is false if the value of x is NaN. You can use this to test whether a value is NaN or not, but the recommended way to test for NaN is with the isnan function (see Floating Point Classes).

How is infinity represented in a C double?

First, 0x7ff0000000000000 is indeed the bit representation of a double infinity. But the cast does not set the bit representation, it converts the logical value of 0x7ff0000000000000 interpreted as a 64 bit integer. So, you need to use some other way to set the bit pattern. However, this is undefined behavior.

How to set an int to infinity in C + +?

Which would be 2^31 – 1 (or 2 147 483 647) if int is 32 bits wide on your implementation. If you really need infinity, use a floating point number type, like float or double. You can then get infinity with: @WTP Considering he needs that for an Dijkstra’s algorithm implementation, I doubt that would be necessary.

Is the existence of Infinity guaranteed by C99?

The existence of INFINITY is guaranteed by C99 (or the latest draft at least), and “expands to a constant expression of type float representing positive or unsigned infinity, if available; else to a positive constant of type float that overflows at translation time.”

Can a floating point number be set to infinity?

If you really need infinity, use a floating point number type, like float or double. You can then get infinity with: Integers are finite, so sadly you can’t have set it to a true infinity. However you can set it to the max value of an int, this would mean that it would be greater or equal to any other int, ie: is always true.