Question

hi i am interested in those chars which are representable by ascii table. for that reason i am doing the following:

       int t(char c) { return (int) c; }
       ...
       if(!(t(d)>255)) { dostuff(); }

so i am interested in only ascii table representable chars, which i assume after conversion to int should be less than 256, am i right? thanks!

Answer 1

char is an integral type in C. You can do the check directly:

char c;
/* assign to c */
if (c >= 0 && c <= 127) {
    /* in ASCII range */
}

I am assuming you don’t want to use isascii() (it’s not in the C standard, although it is POSIX).

Also, you can check if CHAR_MAX is equal to 127. If it is, you don’t need the comparison with 127, since c will not exceed it by definition. Similarly, if CHAR_MIN is 0, then you don’t need the comparison with 0. Both CHAR_MIN and CHAR_MAX are defined in limits.h.

I think you’re thinking about an integer value overflowing a char, and therefore convert it to an int. But, that doesn’t help with overflow since the damage has already been done.