How to accept a string in upper case and print it by lower case with C++ Program

Accept a string in upper case and print it by lower case with C++ Program

# include 
# include  
# include  
using namespace std; 
int main( ) 
{ 
char ch,c; 
cout<<"enter a string in upper case:"; 
while(( ch=getchar( ))!='\n')
{
 c=ch+32; putchar(c);
} 
cout<<" is in lower case"; 
return 0; 
}