compiler-warnings

问题 When I do this: count = ++count; Why do i get the warning - The assignment to variable count has no effect ? This means that count is incremented and then assigned to itself or something else ? Is it the same as just ++count ? What happens in count = count++; ? Why don't I get a warning for this ? 回答1: count++ and ++count are both short for count=count+1 . The assignment is built in, so there's no point to assigning it again. The difference between count++ (also knows as postfix ) and ++count

问题 Recently I tried to use /Wall Visual C++ option to enable all warnings and found that the following code: typedef BOOL ( WINAPI * TIsWow64ProcessFunction )( HANDLE, BOOL* ); TIsWow64ProcessFunction isWow64ProcessFunction = reinterpret_cast<TIsWow64ProcessFunction> ( ::GetProcAddress( kernel32DllHandle, "IsWow64Process" ) ); spawned C4191: warning C4191: 'reinterpret_cast' : unsafe conversion from 'FARPROC' to 'TIsWow64ProcessFunction' Calling this function through the result pointer may cause

问题 This works: int arr[10] = {}; All elements of arr are value-initialized to zero. Why doesn't this work: std::array<int, 10> arr({}); I get the following warning from g++ (version 4.8.2): warning: missing initializer for member ‘std::array<int, 10ul>::_M_elems’ 回答1: There are two issues one which is a matter of style and the warning. Although it may not be obvious, aggregate initialization is happening on a temporary which is then being used as an argument to the copy constructor. The more

问题 I have a problem with [NSString strigWithFormat:format] because it returns an id, and I have a lot of code where I changed a NSString var to an other personal type. But the compiler does not prevent me that there are places where a NSString is going to be set into another type of object. So I'm writing a category of NSString and I'm goind to replace all my calls to stringWithFormat to myStringWithFormat . The code is : @interface NSString (NSStringPerso) + (NSString*) myStringWithFormat:

问题 Like many, I build my project with the an abundance of warning flags. Since not all warning flags are detrimental, the compilation becomes noisy. Warnings such as "unused variables", "shadowing members in initialization lists", "missing switch defaults", are all important to log, but they create too much clutter during builds, and it is hard to spot the important warnings. Given a large project, there can be thousands of warnings mixed in with build statements, and parsing though it

问题 I have many templates in my project. Everything is running fine but I've been getting this warning many times for a long time now. Should I keep ignoring it or should I use #pragma warning(disable : 4199) ? 回答1: Ok Thanks to Simon and Raymond's article I was able to solve it. I no more have that warning anywhere in my code. Just added the command as the article describes at it's very bottom. Here's an image of where exactly I added the command for those like me that might have trouble finding

问题 I have many templates in my project. Everything is running fine but I've been getting this warning many times for a long time now. Should I keep ignoring it or should I use #pragma warning(disable : 4199) ? 回答1: Ok Thanks to Simon and Raymond's article I was able to solve it. I no more have that warning anywhere in my code. Just added the command as the article describes at it's very bottom. Here's an image of where exactly I added the command for those like me that might have trouble finding

问题 I have a Swift function doing something like this: func f() -> Int { switch (__WORDSIZE) { case 32: return 1 case 64: return 2 default: return 0 } } Because __WORDSIZE is a constant, the compiler always gives at least one warning in the switch body. Which lines are actually marked depends on the target I am building for (e.g. iPhone 5 vs. 6; interestingly iPhone 5 gives a warning for the 64-bit case whereas iPhone 6 gives two warnings for 32-bit and default). I found out that the Swift

问题 I have the following C code: #include <math.h> int main(int argc, char ** argv) { double mydouble = 100.0; double whatever = round(mydouble); return (int) whatever; } When I compile this, I get the warnings: round_test.c: In function ‘main’: round_test.c:6: warning: implicit declaration of function ‘round’ round_test.c:6: warning: incompatible implicit declaration of built-in function ‘round’ I'm rusty with C, but I thought that the #include brought a declaration for round() into scope. I've

问题 I have the following C code: #include <math.h> int main(int argc, char ** argv) { double mydouble = 100.0; double whatever = round(mydouble); return (int) whatever; } When I compile this, I get the warnings: round_test.c: In function ‘main’: round_test.c:6: warning: implicit declaration of function ‘round’ round_test.c:6: warning: incompatible implicit declaration of built-in function ‘round’ I'm rusty with C, but I thought that the #include brought a declaration for round() into scope. I've