cout<<(char)toupper(*pos)<<" "; //this works!

cout<<toupper(*pos)<<" "; //without cast it doesn't work, why?

*pos=toupper(*pos);   //and this also doesn't work
cout<<*pos<<" ";

#include <iostream>
#include <list>
 
using namespace std;
 
int main()
{
	list<char> coll;	//this is the container
 
	for(char c='a'; c<='z'; ++c)
		coll.push_back(c);
 
 
	list<char>::iterator pos;
 
	for(pos=coll.begin(); pos!=coll.end(); ++ipos)
	{
		cout<<(char)toupper(*pos)<<" "; //this works!
 
//cout<<toupper(*pos)<<" "; //without cast it doesn't work, why?
 
//*pos=toupper(*pos);   //and this also doesn't work
//cout<<*pos<<" ";
 
	}
	cout<<endl;
	cout<<'A'-0<<endl;
 
}

cout<<toupper(*pos)<<" "; //without cast it doesn't work, why?

*pos=toupper(*pos); //and this also doesn't work
cout<<*pos<<" ";

A 65 A
B 66 B
C 67 C
. .. .
Y 89 Y
Z 90 Z

//Program creates char d, sets it equal to lowercase letter
//Converts it to uppercase and outputs it
#include <cctype>
#include <iostream>
 
using namespace std;
 
int main()
{
    char d='a';  
    d=toupper(d);
    cout<<d;
}

*pos=toupper(*pos); 
cout<<*pos<<" ";

/* 
toupper returns an INT value
toupper(a) will return 65 the ascii value for an uppercase A
*/
 
// the following statement will output the ascii value for the character
cout << toupper(a);
 
// the following statement will cast the INT value to the equivalent CHAR value
cout << (char) toupper(a);

/* for the following examples the compiler will automagically cast the INT values to CHAR without the use of an explicit cast*/
char mychar = 65;
cout << mychar; // will output A
 
char bigchar = 299;
cout << bigchar; // will output a random char as char can only store a value between 0 and 255, your compiler may throw a warning as well