I'd like to know the format specifier of the C bowl type

C supports the boolean type, but there is no format specifier to output true/false. In printf, the format specifier for the bowl is usually %d If you want to print it as true/false, you must specify it separately using a trigonometric operator

bool x = true;
printf("%d\n", x); // 1 output

// To output true or false, select any of the following:
printf(x ? "true" : "false");
//or
printf("%s", x ? "true" : "false");
//or
fputs(x ? "true" : "false", stdout);