Non-Printable Char to int Conversion Issue in C

Current post is on non-printable character conversion to int issue in C language.

By the topic you will assume, what is this? Even a C student who has just started will know that, there is no harm, as we are upgrading the type from character (char) to integer (int).

However, many people including the advanced programmer do not know is that: “conversion of character having non-printable value to int is machine dependent”.

It means that if you take a variable:

char mynonprintablechar = 129;

And then you try to upgrade to int implicitly, the results which you get, will make you scratch your hair.

Example 1: If - Else Statement

if( mynonprintablechar == 129)
     printf(“You expected me”);

else

     printf(“You may get me”);

Example 2: Switch Statement

switch(mynonprintablechar)
{
    case 129:
        printf(“You expected me”);
        break;
    default:
        printf(“You may get me”);
}

The solution:

1. Have unsigned char as variable type.
2. downcast the int against which you compare to char.
3. cast as unsigned char.

Do drop me a mail, if I saved you from scratching your hair :)