# Not understanding why an if statement isn't working
**URL:** https://discourse.cmake.org/t/not-understanding-why-an-if-statement-isnt-working/13983
**Category:** Usage
**Created:** [April 25, 2025, 11:05am UTC](https://discourse.cmake.org/t/not-understanding-why-an-if-statement-isnt-working/13983 "2025-04-25T11:05:18Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@perdrix](https://discourse.cmake.org/u/perdrix)
#### Post date: [April 25, 2025, 11:05am UTC](https://discourse.cmake.org/t/not-understanding-why-an-if-statement-isnt-working/13983/1 "2025-04-25T11:05:18Z")
```auto
message("LINUX: " ${LINUX})
message("APPLE: " ${APPLE})
message("CMAKE_SYSTEM_NAME: " ${CMAKE_SYSTEM_NAME})
if (LINUX OR (APPLE AND ${CMAKE_OSX_ARCHITECTURES} EQUAL "x86_64"))
message("Setting AVX compile options")
:
endif()
```
On macOS and building with CMAKE\_OSX\_ARCHITECTURES set to x86\_64 I get:
```auto
1> [CMake] CMAKE_OSX_ARCHITECTURES: x86_64
1> [CMake] LINUX:
1> [CMake] APPLE: 1
1> [CMake] CMAKE_SYSTEM_NAME: Darwin
```
Note that the message “Setting AVX compile options” wasn’t issued???
I can’t see why not though. Am I being stupid?
D.
---
### Author:  [@marc.chevrier](https://discourse.cmake.org/u/marc.chevrier)
#### Post date: [April 25, 2025, 11:17am UTC](https://discourse.cmake.org/t/not-understanding-why-an-if-statement-isnt-working/13983/2 "2025-04-25T11:17:38Z")
To compare strings, use operator `STREQUAL`.
---
### Author:  [@perdrix](https://discourse.cmake.org/u/perdrix)
#### Post date: [April 25, 2025, 5:13pm UTC](https://discourse.cmake.org/t/not-understanding-why-an-if-statement-isnt-working/13983/3 "2025-04-25T17:13:08Z")
I tried
```auto
message("CMAKE_OSX_ARCHITECTURES: " ${CMAKE_OSX_ARCHITECTURES})
message("LINUX: " ${LINUX})
message("APPLE: " ${APPLE})
message("CMAKE_SYSTEM_NAME: " ${CMAKE_SYSTEM_NAME})
if (LINUX OR (APPLE AND (${CMAKE_OSX_ARCHITECTURES} STREQUAL "x86_64"))
message("Setting AVX compile options")
```
on LINUX and got:
```auto
1> [CMake] CMAKE_OSX_ARCHITECTURES:
1> [CMake] LINUX: 1
1> [CMake] APPLE:
1> [CMake] CMAKE_SYSTEM_NAME: Linux
1> [CMake] CMake Error at DeepSkyStackerKernel/CMakeLists.txt:227 (if):
1> [CMake] if given arguments:
1> [CMake]
1> [CMake] "LINUX" "OR" "(" "APPLE" "AND" "(" "STREQUAL" "x86_64" ")" ")"
1> [CMake]
1> [CMake] Unknown arguments specified
```
clearly my conditional CMake isn’t quite there yet …
D.
---
### Author:  [@LegalizeAdulthood](https://discourse.cmake.org/u/LegalizeAdulthood)
#### Post date: [April 25, 2025, 7:14pm UTC](https://discourse.cmake.org/t/not-understanding-why-an-if-statement-isnt-working/13983/4 "2025-04-25T19:14:55Z")
As shown in the output `CMAKE_OSX_ARCHITECTURES` was empty, so when `${CMAKE_OSX_ARCHITECTURES}` is expanded, it expands to empty text, not an empty string. Try `"${CMAKE_OSX_ARCHITECTURES}"` to get the variable expanded into a string literal and then `STREQUAL` is comparing two string literals.
---
### Author:  [@buildSystemPerson](https://discourse.cmake.org/u/buildSystemPerson)
#### Post date: [April 26, 2025, 4:28am UTC](https://discourse.cmake.org/t/not-understanding-why-an-if-statement-isnt-working/13983/5 "2025-04-26T04:28:26Z")
`CMAKE_OSX_ARCHITECTURES` by default is empty:
[https://cmake.org/cmake/help/latest/variable/CMAKE\_OSX\_ARCHITECTURES.html](https://cmake.org/cmake/help/latest/variable/CMAKE_OSX_ARCHITECTURES.html)
It’s typically set by users. Either on the command line or a toolchain file. That way it’s registered before the first `project` call.
It’s a variable intended for when you want to build a binary with multiple architectures. Apple calls this a universal binary.
---
### Author:  [@perdrix](https://discourse.cmake.org/u/perdrix)
#### Post date: [April 26, 2025, 8:04am UTC](https://discourse.cmake.org/t/not-understanding-why-an-if-statement-isnt-working/13983/6 "2025-04-26T08:04:33Z")
Thank you that works 🙂
David