The ASCII table is arranged so that the value of the character ‘9’ is nine greater than the value of ‘0’; the value of the character ‘8’ is eight greater than the value of ‘0’; and so on. So you can get the int value of a decimal digit char by subtracting ‘0’.
I’m trying to use the char method isLetter(), which is supposed to return boolean value corresponding to whether the character is a letter. But when I call the method, I get an error stating that “char cannot be dereferenced.” I don’t know what it means to dereference a char or how to fix the error. … Read more
The type char is a primitive — not an object — so it cannot be dereferenced Dereferencing is the process of accessing the value referred to by a reference. Since a char is already a value (not a reference), it can not be dereferenced. use Character class:
You can get a specific character from a string simply by indexing it. For example, the fifth character of str is str[4] (off by one since the first character is str[0]). Keep in mind you’ll run into problems if the string is shorter than your index thinks it is. c_str(), as you have in your comments, gives you a char* representation (the … Read more
If your string contains exactly one character the simplest way to convert it to a character is probably to call the charAt method:
You can use Character.toString(char). Note that this method simply returns a call to String.valueOf(char), which also works. As others have noted, string concatenation works as a shortcut as well: But this compiles down to: which is less efficient because the StringBuilder is backed by a char[] (over-allocated by StringBuilder() to 16), only for that array to be defensively copied by the resulting String. String.valueOf(char) “gets in … Read more
It won’t automatically convert (thank god). You’ll have to use the method c_str() to get the C string version. Note that it returns a const char *; you aren’t allowed to change the C-style string returned by c_str(). If you want to process it you’ll have to copy it first: Or in modern C++:
This line doesn’t do the right thing: You want to count by 32, that’s either or I strongly recommend making the numeric and character values match during your output. So change to