---
title: Invalid Boolean value
framework: xcode
role: article
role_heading: Article
path: xcode/invalid-boolean
---

# Invalid Boolean value

Detects when a program accesses a Boolean variable and its value isn’t true or false.

## Overview

Overview Use this check to detect accesses to a Boolean variable when its value isn’t true or false. This problem can occur when using an integer or pointer without an appropriate cast. The use of out-of-range Boolean values has undefined behavior, which can be difficult to debug. Available in Xcode 9 and later. Invalid Boolean variable access in C The intent of the following code is to call the success function when result is nonzero. However, because it uses a Boolean check, the compiler may, as an optimization, only emit instructions that check the least-significant bit of predicate, which is 0, causing a logic error. int result = 2; bool *predicate = (bool *)&result; if (*predicate) { // Error: variable is not a valid Boolean     success(); } Solution Use integer comparison instead of a Boolean check. int result = 2; if (result != 0) { // Correct   success(); }

## See Also

### Undefined Behavior Sanitizer

- [Misaligned pointer](xcode/misaligned-pointer.md)
- [Out-of-bounds array access](xcode/out-of-bounds-array-access.md)
- [Invalid enumeration value](xcode/invalid-enumeration-value.md)
- [Reaching of unreachable point](xcode/reaching-of-unreachable-point.md)
- [Dynamic type violation](xcode/dynamic-type-violation.md)
- [Invalid float cast](xcode/invalid-float-cast.md)
- [Division by zero](xcode/division-by-zero.md)
- [Nonnull argument violation](xcode/nonnull-argument-violation.md)
- [Nonnull return value violation](xcode/nonnull-return-value-violation.md)
- [Nonnull variable assignment violation](xcode/nonnull-variable-assignment-violation.md)
- [Null reference creation and null pointer dereference](xcode/null-reference-creation-and-null-pointer-dereference.md)
- [Invalid object size](xcode/invalid-object-size.md)
- [Invalid shift](xcode/invalid-shift.md)
- [Integer overflow](xcode/integer-overflow.md)
- [Invalid variable-length array](xcode/invalid-variable-length-array.md)