編寫壹個C程序：符號函數

int sign(int x);

int main()

{

int a=1;

while(a!=0)

{

cout<<"Input a number:"<<endl;

cin>>a;

cout<<"Its sign is :"<<sign(a)<<endl;

}

return 0;

}

int sign(int x)

{

if(x>0) return 1;

if(x<0) return -1;

else return 0;

}