You're probably mixing up terms here as QWERTY is the name given to a standard English keyboard; there is no such thing as a "QWERTY word". If you simply want to test if a given word is composed of letters, digits or other symbols within a given subset of characters, then use the String.IndexOfAny() method to compare each character in turn against a fixed array of accepted characters.
void printStarts (void);
void abc(int); is a function declaration. The declared function has no return value, is named abc and accepts one integer argument by value.
double calcAreaRect (double a, double b);
The function already exists in PHP and is even called max(); Otherwise use: function max ($one, $two) { return $one > $two ? $one : $two; }
strlen is the C library function that accepts a pointer to a char array and returns an integer specifying the number of characters (in bytes) of the array. This function is usually not used any more, because it does not support multi-byte characters, such as UTF-8.
void printStarts (void);
void abc(int); is a function declaration. The declared function has no return value, is named abc and accepts one integer argument by value.
double calcAreaRect (double a, double b);
Pope Benedict is now retired and, as best I can determine, accepts few visitors.
A Bronsted-Lowry acid is a substance that donates a proton (H) in a chemical reaction, while a Bronsted-Lowry base is a substance that accepts a proton. To determine if a substance is a Bronsted-Lowry acid or base, you can look at its behavior in a reaction - if it donates a proton, it is an acid, and if it accepts a proton, it is a base.
float test(int, char);
Not necessarily. A function that accepts one or more arguments may process those arguments but need not return any value to the caller. In this case the function simply returns void.
question clarity
The function already exists in PHP and is even called max(); Otherwise use: function max ($one, $two) { return $one > $two ? $one : $two; }
The plural of "accept" is "accepts."
he/she accepts
An encoder is a digital circuit which accepts one of the inputs and converts it into BCD or Binary Coded Output. It performs the reverse function of that of a decoder.