Question

I have an array of characters populated by cin, but im trying to find a way to check each character individually to make sure its only one of a set number of characters (a-z,A-Z,0-9,[space]).

The easiest way I thought this could be done is to check if the code of the character fell within a certain range. But not sure how to get it.

Alternatively if anyone knows any other ways of doing it, that would be great.

Answer 1

The easiest way is to use isalpha(), isdigit() or isalnum():

char ch = ...  //  The character

//  Original solution
if (isalpha(ch) || isdigit(ch)){

}

//  Better solution by fefe (see comments)
if (isalnum(ch)){

}

These are defined in ctype.h: http://www.cplusplus.com/reference/clibrary/cctype/

Otherwise you can also use comparisons:

if ('a' <= ch && ch <= 'z' ||
    'A' <= ch && ch <= 'Z' ||
    '0' <= ch && ch <= '9'
){

}

This latter approach using comparisons will generalize to arbitrary ranges.