fixed ReadingLab/Discussion-for-Cpp#22
fixed ReadingLab/Discussion-for-Cpp#22

wgs111/CppPrimer,vzyw/CppPrimer,heamon7/CppPrimer,cseryp/CppPrimer,laohei889/CppPrimer,wgs111/CppPrimer,lawlietye/CppPrimer,jwave/CppPrimer,akanezorap/CppPrimer,jieniyimiao/CppPrimer,sheldon66/CppPrimer,sheldon66/CppPrimer,sunday1103/Cpp-Primer,floristt/CppPrimer,cheng668/CppPrimer,vzyw/CppPrimer,laohei889/CppPrimer,floristt/CppPrimer,anguszxd/CppPrimer,at86/CppPrimer,shuidong/CppPrimer,akanezorap/CppPrimer,cheng668/CppPrimer,zhangzhizhongz3/CppPrimer,Sublele/CppPrimer,m0000re/CppPrimer,Sublele/CppPrimer,Milk-SF/CppPrimer,Milk-SF/CppPrimer,cseryp/CppPrimer,at86/CppPrimer,jwave/CppPrimer,heamon7/CppPrimer,zhangzhizhongz3/CppPrimer,pezy/CppPrimer,FingerSport/CppPrimer,pezy/CppPrimer,FingerSport/CppPrimer,m0000re/CppPrimer,lawlietye/CppPrimer,shuidong/CppPrimer