get the abs value of long long integer

Question

I try to use the codes below to get the abs value of a long long type integer;

long long v=abs(originalValue);

It works as I expected until the value of v exceeds 1073741824 (1G)

If v is 2147482648, abs(v) is -2147482648.

If v is 10737418240, abs(v) is -2147482648 also.

I do not understand what causes these happened.

Welcome any comment

Thanks

interdev

Answer 1

abs takes an int as an argument, for a long long use llabs

Answer 2

Use llabs() instead:

long long v = llabs(originalValue);