what is nan in c

What is Nan in math?

NaN, acronym for “Not a Number” is an exception which usually occurs in the cases when an expression results in a number that can’t be represented. For example square root of negative numbers. How to check for NaN ?

How to check for Nan in C++?

How to check for NaN in C++? Method 1: Using compare (“==”) operator. In this method, we check if a number is complex by comparing it with itself. If the result is true, then the number is not complex i.e., real. But if the result is false, then “nan” is returned, i.e. the number is complex.

What is Nan exception in C++?

NaN, acronym for “Not a Number” is an exception which usually occurs in the cases when an expression results in a number that can’t be represented. For example square root of negative numbers. // C++ code to demonstrate NaN exception

What does Nanan mean in C language?

NaN, acronym for “Not a Number” is an exception which usually occurs in the cases when an expression results in a number that can’t be represented. For example square root of negative What are the biggest money secrets that rich people keep from us? Here are the five biggest secrets they never share. What does % stand for in C language?

What is a NaN value?

In computing, NaN (/næn/), standing for Not a Number, is a member of a numeric data type that can be interpreted as a value that is undefined or unrepresentable, especially in floating-point arithmetic.

Is NaN function in C?

In C, the isnan macro and the _isnan and _isnanf functions return a non-zero value if the argument x is a NaN; otherwise they return 0. In C++, the isnan template function returns true if the argument x is a NaN; otherwise it returns false .

What produces NaN in C?

nan is produced when we program contain value like 0.0/0.0 as said by @Dan Cecile OR sqrt(-1). Highly active question.

What type of data is NaN?

NaN (Not a Number) is a numeric data type that means an undefined value or value that cannot be represented, especially results of floating-point calculations.

Is NaN is null?

Within pandas, a missing value is denoted by NaN . In most cases, the terms missing and null are interchangeable, but to abide by the standards of pandas, we'll continue using missing throughout this tutorial.

Is NaN and null the same?

NaN : means 0/0 -- Stands for Not a Number NA : is generally interpreted as a missing, does not exist NULL : is for empty object.

What is NaN function?

isNaN() returns true if a number is Not-a-Number. In other words: isNaN() converts the value to a number before testing it.

Is NaN a variable?

Description. NaN is a property of the global object. In other words, it is a variable in global scope. The initial value of NaN is Not-A-Number — the same as the value of Number.

Is NaN a string or float?

NaN stands for Not A Number and is one of the common ways to represent the missing value in the data. It is a special floating-point value and cannot be converted to any other type than float.

Why NaN is a number?

NaN just means the specific value cannot be represented within the limitations of the numeric type (although that could be said for all numbers that have to be rounded to fit, but NaN is a special case). A specific NaN is not considered equal to another NaN because they may be different values.

Is NaN a keyword?

Regarding your second point: They are not needed, that's why undefined and NaN are not keywords. @Baszz - by that logic it should be possible to overwrite the value of true , false , null , etc., but it isn't.

How do you use NaN?

NaN , standing for not a number, is a numeric data type used to represent any value that is undefined or unpresentable. For example, 0/0 is undefined as a real number and is, therefore, represented by NaN.

Is NaN a function?

The isNaN() function is used to check whether a given value is an illegal number or not. It returns true if value is a NaN else returns false. It is different from the Number.

Is NaN or == NaN?

NaN is not equal to NaN! Short Story: According to IEEE 754 specifications any operation performed on NaN values should yield a false value or should raise an error. Thanks CJ J for sharing this. TLDR; is "Because the IEEE standard says so".

Is NaN a condition?

NaN values are generated when arithmetic operations result in undefined or unrepresentable values. Such values do not necessarily represent overflow conditions. A NaN also results from attempted coercion to numeric values of non-numeric values for which no primitive numeric value is available.

Is NaN undefined or null?

null : It means that the object is empty and isn't pointing to any memory address. A bit more informally and concisely NaN - "not a valid number" usually after you did some operation that should produce one but couldn't. undefined - it exists but hasn't been given a value yet.

What does IEEE 754 mean?

IEEE 754 floating point numbers can represent positive or negative infinity, and NaN (not a number). These three values arise from calculations whose result is undefined or cannot be represented accurately. You can also deliberately set a floating-point variable to any of them, which is sometimes useful. Some examples of calculations that produce infinity or NaN:

What is math.h macro?

math.h defines macros that allow you to explicitly set a variable to infinity or NaN.

What is the entry point of a C program?

The entry point to a C program is a function called ‘main’, with return type ‘int’, and either no arguments, or two arguments (one of type int, the other of type pointer to pointer to char): int main (void) or int main (int a, char **b) (“a” and “b” are arbitrary names).

What is C programming?

C is a programming language for computer developed in 1972 by Dennis Ritchie. C provides the benefit of cross-platform programming and is a good substitute for the old assembly language coding program, which was a pretty complex one. It has a static type structure that prevents any unintended operations.

What does void mean in main?

Nothing has been said about the arguments in main, which means that you can either pass the arguments to main or not pass anything at all. void main (void) The return type of the function "main" is void, i.e. it does not return anything to the OS. "void" means that you're not allowed to pass any argument to the main.

What is the use of #ifdef NAN?

You can use ‘#ifdef NAN’ to test whether the machine supports NaN. (Of course, you must arrange for GNU extensions to be visible, such as by defining _GNU_SOURCE, and then you must include math.h.)

What is a macro not a number?

An expression representing a value which is “not a number”. This macro is a GNU extension, available only on machines that support the “not a number” value—that is to say, on all machines that support IEEE floating point.

What is the meaning of "back up"?

Making statements based on opinion; back them up with references or personal experience.

What is the floating point format for X86?

This should work on any processor which uses the IEEE 754 floating point format (which x86 does).

Why do new compilers always switch off traps?

But the new compilers almost always switch the traps off and return the given values because trapping interferes with error handling.

Is NAN a constant expression?

NAN may or may not be defined, and "is defined if and only if the implementation supports quiet NaNs for the float type. It expands to a constant expression of type float representing a quiet NaN."

Does C++ support NAN?

There is no compiler independent way of doing this, as neither the C (nor the C++) standards say that the floating point math types must support NAN or INF.

Is 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."

Is 1e309 a double literal?

which works at least in IEEE 754 contexts because the highest representable double value is roughly 1e308. 1e309 would work just as well, as would 1e99999, but three nines is sufficient and memorable. Since this is either a double literal (in the #define case) or an actual Inf value, it will remain infinite even if you're using 128-bit (“long double”) floats.

What is macro isnan in C99?

For C99, in C, this is implemented as a macro isnan (c) that returns an int value. The type of x shall be float, double or long double.

How to check for NaN?

The supposedly portable way to check for NaN is to use the IEEE 754 property that NaN is not equal to itself: i.e. x == x will be false for x being NaN.

Is C99 isnan available in C++?

Moreover, some implementations of C++ still make C99 isnan () macro available for C++ (included through cmath or math.h ), what may cause more confusions and developers may assume it's a standard behaviour.

Does cmath include C99?

If TR1 is available, then cmath includes C99 elements like isnan (), isfinite (), etc. but they are defined as functions, not macros, usually in std::tr1:: namespace, though many implementations (i.e. GCC 4+ on Linux or in XCode on Mac OS X 10.5+) inject them directly to std::, so std::isnan is well defined.

What is the meaning of "back up"?

Making statements based on opinion; back them up with references or personal experience.

What is the result of 0.f/FLT_MIN?

In the example above, the result of ( 0.f/FLT_MIN) will be 0, basically. You may want 0.0/0.0 to generate HUGE instead. So,

Does nan produce bugs?

In my own code, I noticed that nan values tend to produce difficult to find bugs. (Note how this is not the case for inf or -inf. ( -inf < 0) returns TRUE, ( 0 < inf ) returns TRUE, and even ( -inf < inf) returns TRUE. So, in my experience, the behavior of the code is often still as desired).

What does nan mean in C++?

NaN is used for indicating a number that cannot be represented. For example, the square root of negative numbers, zero divided by zero, etc. NaN stands for “Not a Number”. In this tutorial, we will see some examples of nan in C++.

What is the property of nan values?

There is an interesting property of nan values and that is that they return false when compared to themselves. Which means the following expression will give the result as false.