Answers for "char at c++ string"

char c++

isdigit() - Check if character is decimal digit 
isalpha() - Check if character is alphabetic
isblank() - Check if character is blank
islower() - Check if character is lowercase letter
isupper() - Check if character is uppercase letter
isalnum() - Check if character is alphanumeric

char at in c++

str.at(index)