is there any problem to use abs instead of labs or fabs?

Question

I would like to know the difference of abs,labs and fabs. This is under the cstdlib header file. So, I got confused to use these words in cpp programming.

they are different functions for different datatypes. What confuses you? — 463035818_is_not_an_ai, Mar 06 '20 at 12:08
What would you like to know that's not on https://en.cppreference.com/w/cpp/numeric/math/abs? As-is, this question is too broad to be answered. — YSC, Mar 06 '20 at 12:10
what specifically you dont understand? We cannot know what is your current level, for example it could be that you dont know how to call a function. Do you know how to call a function? — 463035818_is_not_an_ai, Mar 06 '20 at 12:10
Example of on-topic question: "_In the following [mcve] `#include — YSC, Mar 06 '20 at 12:11

anastaciu · Answer 1 · 2020-03-06T12:27:09.343

1

int abs(int n)

This function returns the absolute value of n being n an int variable.

long int labs(long int n)

This function returns the absolute value of parameter n as long int type instead of int.

float fabs(float n)

This function returns the absolute value of parameter n as float type variable.

There are still these overloads for double and long double types:

double fabs (double x); //for double variables
long double fabs (long double x); //for long double variables

For these overloads the compiler will choose the correct version deppending on the parameter type.

The difference is clear, you should use the correct version of abs() deppending on the parameter variable type you are using, the wrong usage may result in undefined behavior namely due to signed integer overflow.

edited Mar 06 '20 at 12:27

answered Mar 06 '20 at 12:14

anastaciu

23,467
7
28
53

your last sentence can be misread. There are implicit conversions, so the type of the parameter must not necessarily be the same as the type of the argument. – 463035818_is_not_an_ai Mar 06 '20 at 12:16
@idclev463035818, yes, I changed it. – anastaciu Mar 06 '20 at 12:18

score 1 · Answer 2 · answered Mar 06 '20 at 12:14

the only difference is the return type and the parameter type. abs() takes an integer as a parameter and also return an integer, fabs() takes and returns a floating point type like a float or double labs() takes and returns a long int. So simply use the appropriate one for the data you're dealing with. check this link https://learntechway.com/abs-fabs-labs-in-c/

is there any problem to use abs instead of labs or fabs?

2 Answers2