The code uses an operator for assignment when the intention was to perform a comparison.
Extended description
In many languages the compare statement is very close in appearance to the assignment statement and are often confused. This bug is generally the result of a typo and usually causes obvious problems with program execution. If the comparison is in an if statement, the if statement will usually evaluate the value of the right-hand side of the predicate.
Best practices to prevent this CWE
Phase: Testing
Many IDEs and static analysis products will detect this problem.
Phase: Implementation
Place constants on the left. If one attempts to assign a constant with a variable, the compiler will produce an error.