function should return a value; 'void' return type assumed

#include<iostream> using namespace std; void sphere(); int main() { sphere(); //return 0; } void sphere() { double radius; cout<<"Please input radius:"; cin>>radius; if (radius<0) return; cout<<"The result is "<<radius*radius*3.14*4<<"/n"; //return 0; }

--------------------Configuration: ex - Win32 Debug--------------------
Compiling...
ex01.cpp
D:/960174/My Documents/VC/ex/ex01.cpp(8) : warning C4508: 'main' : function should return a value; 'void' return type assumed
Linking...

ex.exe - 0 error(s), 1 warning(s)

 

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有返回值的函數無任在任何條件下都必須有返回值,