bc: Precedence
3.5 Precedence
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The expression precedence is as follows: (lowest to highest)
|| operator, left associative
&& operator, left associative
! operator, nonassociative
Relational operators, left associative
Assignment operator, right associative
+ and - operators, left associative
*, / and % operators, left associative
^ operator, right associative
unary - operator, nonassociative
++ and -- operators, nonassociative
This precedence was chosen so that POSIX compliant 'bc' programs will
run correctly. This will cause the use of the relational and logical
operators to have some unusual behavior when used with assignment
expressions. Consider the expression:
a = 3 < 5
Most C programmers would assume this would assign the result of "3 <
5" (the value 1) to the variable "a". What this does in 'bc' is assign
the value 3 to the variable "a" and then compare 3 to 5. It is best to
use parentheses when using relational and logical operators with the
assignment operators.