compiler-flags

My project contains XMPPFramework which contains a file that has to be used with ARC. But my project is Non ARC and cannot be converted due to certain other libraries linked to it. How do I force the compiler to use ARC only on a certain class ? justin It is the inverse problem of this question . The difference is that you would use -fobjc-arc instead of -fno-objc-arc . 来源： https://stackoverflow.com/questions/13392521/how-to-force-xcode-to-use-arc-on-a-specific-file

For the GCC CFLAGS options: -msse , -msse2 , -mssse3 , -msse4 , -msse4.1 , -msse4.2 . Are they exclusive in their use or can the be used together? My understanding is that the choosing which to set depends on whether the target arch, which the program will run on, supports it or not, is this correct? If so, how could I know what sse my target arch supports? In Linux, I cat /proc/cpuinfo, but what if mac or Windows? Thanks! The -m switched can be used in parallel, furthermore some of them are implied by the architecture or other switches. For instance, if you build code for x86_64, -msse -msse2

Why the output of this program is 4 ? #include <iostream> int main() { short A[] = {1, 2, 3, 4, 5, 6}; std::cout << *(short*)((char*)A + 7) << std::endl; return 0; } From my understanding, on x86 little endian system, where char has 1 byte, and short 2 bytes, the output should be 0x0500 , because the data in array A is as fallow in hex: 01 00 02 00 03 00 04 00 05 00 06 00 We move from the beginning 7 bytes forward, and then read 2 bytes. What I'm missing? You are violating strict aliasing rules here. You can't just read half-way into an object and pretend it's an object all on its own. You can

From the documentation's description, they seem to do the same thing except that "not all systems" support shared and "only some systems" support symbolic (it's unclear if these are the same set of systems): -shared Produce a shared object which can then be linked with other objects to form an executable. Not all systems support this option. For predictable results, you must also specify the same set of options that were used to generate code (-fpic, -fPIC, or model suboptions) when you specify this option.[1] -symbolic Bind references to global symbols when building a shared object. Warn

At the beginning of my CMake project, I'm setting general compilation flags in the variable CMAKE_CXX_FLAGS, like set(CMAKE_CXX_FLAGS "-W -Wall ${CMAKE_CXX_FLAGS}") Later on, I need to append additional configuration-specific compilation flags (stored in BUILD_FLAGS). Can I use the following command for this: set_target_properties(${TARGET} PROPERTIES COMPILE_FLAGS ${BUILD_FLAGS}) or do I have to add the CMAKE_CXX_FLAGS manually: set_target_properties(${TARGET} PROPERTIES COMPILE_FLAGS "${CMAKE_CXX_FLAGS} ${BUILD_FLAGS}") to prevent CMAKE_CXX_FLAGS being overriden by BUILD_FLAGS? Use the first