c++ printing unsigned char values

Asked Dec 29 '17 at 15:07

Active Dec 29 '17 at 15:07

Viewed 2,226 times

Consider the following:

int main() {
    unsigned char val(-1); 
    printf( "val = %u\n", val );
    return 0;
}

Ouptut:

val = 255

However when I try to use iostream

int main() {
    unsigned char val(-1);
    std::cout << "val = " << val << std::endl;
}

Output:

val =

Yet in the debugger when I check val it has the value 255 with the y with double dots above the y.

How can I get iostream to print out the same as printf() with the value of 255

asked Dec 29 '17 at 15:07

Francis Cugler

3

`std::cout << "val = " << +val << std::endl;` I'll look for a dupe. – Baum mit Augen Dec 29 '17 at 15:09
Okay sure; no problem. – Francis Cugler Dec 29 '17 at 15:10
I'd argue a cast to `unsigned` is a bit clearer. – DeiDei Dec 29 '17 at 15:10
Wow; that did it; something so simple but forget the reason... – Francis Cugler Dec 29 '17 at 15:10
1

@DeiDei Agreed, but how else am I supposed to show off I know integer promotion rules? ;) – Baum mit Augen Dec 29 '17 at 15:11
@BaummitAugen Good point. – DeiDei Dec 29 '17 at 15:12
@DeiDei for my purposes the promotion is better than a cast... I'm using it in a class template that takes any integral type `T` and in the `operator<<()` I'm printing out based on the `unsigned version` of `T`. – Francis Cugler Dec 29 '17 at 15:13

0 Answers0