Programming Languages
Many programming languages use precedence levels that conform to the order commonly used in mathematics, though some, such as APL and Smalltalk, have no operator precedence rules (in APL evaluation is strictly right to left, in Smalltalk it's strictly left to right).
The logical bitwise operators in C (and all programming languages that borrowed precedence rules from C, for example, C++, Perl and PHP) have a precedence level that the creator of the C language considers to be unsatisfactory. However, many programmers have become accustomed to this order. The relative precedence levels of operators found in many C-style languages are as follows:
| 1 | -> . :: | Grouping, scope, array/member access |
| 2 | ! ~ - + * & sizeof type cast ++x --x | (most) unary operations, sizeof and type casts |
| 3 | * / % | Multiplication, division, modulo |
| 4 | + - | Addition and subtraction |
| 5 | << >> | Bitwise shift left and right |
| 6 | < <= > >= | Comparisons: less-than, ... |
| 7 | == != | Comparisons: equal and not equal |
| 8 | & | Bitwise AND |
| 9 | ^ | Bitwise exclusive OR |
| 10 | | | Bitwise inclusive (normal) OR |
| 11 | && | Logical AND |
| 12 | || | Logical OR |
| 13 | ?: = += -= *= /= %= &= |= ^= <<= >>= | Conditional expression (ternary) and assignment operators |
| 14 | , | Comma operator |
Examples:
!A + !B≡(!A) + (!B)++A + !B≡(++A) + (!B)A + B * C≡A + (B * C)A || B && C≡A || (B && C)(A && B == C)≡(A && (B == C) )
The accuracy of software developer knowledge about binary operator precedence has been found to closely follow their frequency of occurrence in source code.
Read more about this topic: Order Of Operations
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