在C ++中放置默认参数值的位置？ [重复]
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函数参数的默认值
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黎喊病
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贡炮逗握惫
void foo(int x = 42, int y = 21); void foo(int x /* = 42 */, int y /* = 21 */) { ... }邪罗逢确胃
在那个类的源文件中，我有int CI2cHal::SetI2cSlaveAddress( UCHAR addr, bool force = false ) { ... }假设它将“force”参数视为“false”'被授予'。 但是，编译器（放入c ++ 11模式）抱怨并给了我以下编译器错误：/home/.../mystuff/domoproject/lib/i2cdevs/max6956io.cpp: In member function 'void CMax6956Io::Init(unsigned char, unsigned char, unsigned int)': /home/.../mystuff/domoproject/lib/i2cdevs/max6956io.cpp:26:30: error: no matching function for call to 'CMax6956Io::SetI2cSlaveAddress(unsigned char&)' /home/.../mystuff/domoproject/lib/i2cdevs/max6956io.cpp:26:30: note: candidate is: In file included from /home/geertvc/mystuff/domoproject/lib/i2cdevs/../../include/i2cdevs/max6956io.h:35:0, from /home/geertvc/mystuff/domoproject/lib/i2cdevs/max6956io.cpp:1: /home/.../mystuff/domoproject/lib/i2cdevs/../../include/i2chal/i2chal.h:65:9: note: int CI2cHal::SetI2cSlaveAddress(unsigned char, bool) /home/.../mystuff/domoproject/lib/i2cdevs/../../include/i2chal/i2chal.h:65:9: note: candidate expects 2 arguments, 1 provided make[2]: *** [lib/i2cdevs/CMakeFiles/i2cdevs.dir/max6956io.cpp.o] Error 1 make[1]: *** [lib/i2cdevs/CMakeFiles/i2cdevs.dir/all] Error 2 make: *** [all] Error 2并从基类的源文件中删除它：那么编译器很高兴并且所有代码都按预期工作（我可以给函数ѭ7提供一个或两个参数）！ 因此，不仅对于类的用户而言，将参数的默认值放在头文件中也很重要，同时编译和功能明智，这显然是必须的！桑娠贯涤
盛虱
锑寝粒
void testFunct(int nVal1, int nVal2=500); void testFunct(int nVal1, int nVal2) { using namespace std; cout << nVal1 << << nVal2 << endl; }谷靛
struct iface { virtual void test(int a = 0) { std::cout << a; } }; struct impl : public iface { virtual void test(int a = 5) override { std::cout << a; } }; int main() { impl d; d.test(); iface* a = &d; a->test(); }我强烈反对你这样使用它购藏盗码韦
冕偷淮款
//declaration void function(char const *msg, bool three, bool two, bool one = false); void function(char const *msg, bool three = true, bool two, bool one); // Error void function(char const *msg, bool three, bool two = true, bool one); // OK //void function(char const *msg, bool three = true, bool two, bool one); // OK int main() { function("Using only one Default Argument", false, true); function("Using Two Default Arguments", false); function("Using Three Default Arguments"); return 0; } //definition void function(char const *msg, bool three, bool two, bool one ) { std::cout<<msg<<" "<<three<<" "<<two<<" "<<one<<std::endl; }