From 71d83ce4669754bacdf4a51071cbc40ca4e72706 Mon Sep 17 00:00:00 2001 From: light-city <455954986@qq.com> Date: Tue, 6 Aug 2019 14:50:15 +0800 Subject: [PATCH] update dir --- README.md | 3 ++- explicit/README.md | 10 ++++++++++ explicit/explict | Bin 0 -> 9288 bytes explicit/explict.cpp | 46 +++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 58 insertions(+), 1 deletion(-) create mode 100644 explicit/README.md create mode 100755 explicit/explict create mode 100644 explicit/explict.cpp diff --git a/README.md b/README.md index 085b490..64156ea 100644 --- a/README.md +++ b/README.md @@ -21,7 +21,8 @@ - [x] [struct那些事](./struct) - [x] [struct与class那些事](./struct_class) - [x] [union那些事](./union) -- [x] [c实现c++多态](./c_poly) +- [x] [c实现c++多态那些事](./c_poly) +- [x] [explicit那些事](./explicit) 代码运行： 全部在linux下用vim编写，使用gcc/g++调试！全部可正常运行！ diff --git a/explicit/README.md b/explicit/README.md new file mode 100644 index 0000000..8fbe13f --- /dev/null +++ b/explicit/README.md @@ -0,0 +1,10 @@ +# explicit(显式)关键字那些事 + +- explicit 修饰构造函数时，可以防止隐式转换和复制初始化 +- explicit 修饰转换函数时，可以防止隐式转换，但按语境转换除外 + + +代码参见:[./explict.cpp](./explicit.cpp) + +参考链接： +> https://stackoverflow.com/questions/4600295/what-is-the-meaning-of-operator-bool-const diff --git a/explicit/explict b/explicit/explict new file mode 100755 index 0000000000000000000000000000000000000000..888e363d011400d15fd013a52ce83edebb45c046 GIT binary patch literal 9288 zcmeHNeQaCR6~DHVH2uJFp|H{->OniwvY5C{Lka_ICuv{0^n)gajuBoQ+i4zk?8<&F zX{BzU6sYOSqQSII+O#4z1RB~pfwYcIZK@&)+WvrT@DGIrM!S@cQ3O<(R+|0JefK;+ zzc>tO+F#qP{LVeU^L4-9yC?m2d*^De$0N9S#m$1a#+rzPtfvrruaK<5TEt8d5sSnX zq6SDcei11lYSoxdDA!DDm7Wi@3cnVw1+;i0vci#w% zhwJj!yz=v3Kl9LT(x)Ndc@qL2!Kh&oOWR-Vgm~IQ@q-nli>ATv1AcJ@{bSSM&rXA{ z03O88T{Zv+xMd ztw!EV)R8gF zws89np-;tI2}ipU+$6Lnu}x15Y}5PWMjCBQ48`@hnHn-oFr=v(JQz1JVohg9tW{qg zYO-s~Lo2QNmM!`U;Hr4BVrb3K3R24wOTsID2!!Ul5x;qcfgN5Y{-m(N0s~9NC*A;0 z#UuY&`ox<{zlSaB6=#S+nW*cPl=hNG)~v_;K(DOKz|(4jg$Ert??sZ-J8-S?-9Ktpk8hLU^R>rGD#YZ<7(|mx+VHGf6hV#n0TP`V zn?zZ11M$?AGcQYiIq@`nXGSHzjCktOnM0Dlig@bEnS+x5w*aaUPXvMSIvGH3p&kNcs7tBj- zZ?oB3-6GL*+=_qiO$OR83UfEZa6E&C^}JAh8z9feGSbli4s>n!7E!2v?-AJ9&ORc8 z$(MW1?1Bx|M|zGsNEariKB?`iT2fDaDYlP?N45R!uOFe2)`};_x1j>yqz&9*0dLqq zhXuT811%Qt7aO?70^YWP%Lu@V=o-Hptbp#>bnW{G5i`5n_*u8Z4^_ zuo27p2Z-2v^pj{osa~;K3JC~l4d-B+4zH$9LdUXE>W-$CZuh-7vyPd^zZSXKT z@1!<-+@q~}ukbErs`i^b(L19((YvDh@sU!v@zxSV$lf9(s53Kgj zUt2f(p4xlGEemd3wqo&B1d~r36C#4P%TKJRKk$IJ^`e>%1Xl7SXbAE;P{H!GCHWq} zSALHDPa&W4Irh(!J^DpwyX`+#^8XIt>S^SQA*;ezzK?!JL2di?VW01MkL3g~_4BKc zS7WYjM%~uiS&GvM`PGnL>XdJ^^G9<2mZ-lm>aUOagV2M1%wH?NyPk!gz3^kLG;;R;@;^5Mcu!M#rq-fk zH5Mg|3YLg0Zc5);RMa&~9ITE=p3W&Md+-@R<#PF?`&O^4EmV9!(FKau;`K{Ko-LrX z=c#;pVKPhffHy+KzVjXOSv=o$M!gn4OIYPoMQ1BIUs1WIRGkQY@W_I<3l-iALz1)Z zCsdVZ0_c|%Ua$JgctG*oZjQ&_cFg1Wk^LF1ibzj5awX4k&no^2C0F78>xA#I?m(}p zew|kIoT4>qom}QxFKoZ2we^Nz{pP+x#w-L^hMGc+4b26~g})VU4mCD~!r`TsAh^6S z+}zmQxQcD3qdu(07H?#V*oRr`u88}DSrMsL}gARblgf#d!`;tK?Ql~ZB-b=0X} z1@%6W-#EZ#LxFI9&+s`+c9r5@4S@$4k=i*CXp~A=;#0?&G%ESIi2{hJ>vp5`Gj*Nx zOZ`ixtj~KC&hIhuO64KxXX^SqgabW@x1W2xJp%o!FbL4};dIq>mOlfh z{=Vj#uQA{>{*>;ZBEQ8!&nmn@?YkLLD#Sm42SjQADp*wG1Ef;k@5{g`?u)MVut3g> zUwp;oKL?!rZ*jH%TKJ)HaG!6>r}6(a*&e^3{0$X(mjQiO_N&7CD3LSsW}&}7lt4;v zZR;kzv!kmU8OTziQ8x$m1f?30g4B~)eQP?~7fon@xqWuWCypWQ)Vg|x_;%V zrpiiszmYNYcrF*;si!h#Zl~za#RpS*vM@Nf6DAH$ho)Jkni|@kHWFqiv3)!8mR)9N zc-3|zl}O!V{{Xx!>e(RJ;5`}#J@%*sLHI?~>HyQUPhwoSH^ z4XamowRh{?(O73Y8I|=ZSq{jguh84Ru|B%4qm?qVUk}F;JNm3FZ8(O!ELvyfTNC+$ z97^#2K4Dxr#T$vpOs&evA{rtrFGa9Y(3H_tib&~FBG;MybxEeip%k+#&gW*YH(;KU zMn*5>Qy3glt(?r(lW{X{C7sbAq`>W2N#?Wq0H&3a;WU6zHGrjIQ;Pz#8Vko@-IveX zp2{=brS4%hV|=3445TQy0%*Ww)?0+~I|t2pAE=qL=m6J@4AS@8MJSUsQ=w?Aqrr@C zRovE0A=Fne@OKv@DMG{z#Pb6pl-!wtKZ}|H)+V4reFYwM|4tGF~f501&ng?9=)e2UiMEaITLBdiUwpD~e70wN52R!tv()T+S-mnCQaG_> zz5nkIF%HPdljWIp1MPtyo+qTEx$3&-c7hW#3Cmj>35qrjJ7Av=7!qq;^m> zh}+99-29JS_WXU>sO&eXb-?x8YiD^147H!fB&{5pu_Y!3E?asr*_XYmDx_i9b z_OHU0?gVVl_vBi2A#m%v`L|$8O=Nq%PY1rB{b|_JRI@$jh4}wHjH&*sJgsEdxfz05QH&}DDm<5hqN_=cxL#o literal 0 HcmV?d00001 diff --git a/explicit/explict.cpp b/explicit/explict.cpp new file mode 100644 index 0000000..f659635 --- /dev/null +++ b/explicit/explict.cpp @@ -0,0 +1,46 @@ +#include + +using namespace std; + +struct A +{ + A(int) { } + operator bool() const { return true; } +}; + +struct B +{ + explicit B(int) {} + explicit operator bool() const { return true; } +}; + +void doA(A a) {} + +void doB(B b) {} + +int main() +{ + A a1(1); // OK：直接初始化 + A a2 = 1; // OK：复制初始化 + A a3{ 1 }; // OK：直接列表初始化 + A a4 = { 1 }; // OK：复制列表初始化 + A a5 = (A)1; // OK：允许 static_cast 的显式转换 + doA(1); // OK：允许从 int 到 A 的隐式转换 + if (a1); // OK：使用转换函数 A::operator bool() 的从 A 到 bool 的隐式转换 + bool a6(a1); // OK：使用转换函数 A::operator bool() 的从 A 到 bool 的隐式转换 + bool a7 = a1; // OK：使用转换函数 A::operator bool() 的从 A 到 bool 的隐式转换 + bool a8 = static_cast(a1); // OK ：static_cast 进行直接初始化 + + B b1(1); // OK：直接初始化 +// B b2 = 1; // 错误：被 explicit 修饰构造函数的对象不可以复制初始化 + B b3{ 1 }; // OK：直接列表初始化 +// B b4 = { 1 }; // 错误：被 explicit 修饰构造函数的对象不可以复制列表初始化 + B b5 = (B)1; // OK：允许 static_cast 的显式转换 +// doB(1); // 错误：被 explicit 修饰构造函数的对象不可以从 int 到 B 的隐式转换 + if (b1); // OK：被 explicit 修饰转换函数 B::operator bool() 的对象可以从 B 到 bool 的按语境转换 + bool b6(b1); // OK：被 explicit 修饰转换函数 B::operator bool() 的对象可以从 B 到 bool 的按语境转换 +// bool b7 = b1; // 错误：被 explicit 修饰转换函数 B::operator bool() 的对象不可以隐式转换 + bool b8 = static_cast(b1); // OK：static_cast 进行直接初始化 + + return 0; +}