Input Checker Function

A function to check and validate different 5 types of input

About: the check() function performs different types of validation checks based on the value of the enum type parameter.

1. Included Header File:

#include "includes.h"

This line includes a header file named "includes.h" (see in #1.-included-header-file). This header file likely contains the necessary include statements for required libraries and dependencies. By including this file, all the necessary libraries are made available for the code to work properly. Here we need it to import the stdarg.h , string.h and ctype.h library (explained in )

2. Enum Type:

enum type {isAlpha, isEmail, coef, avg, age};

This line declares an enumeration type named type that represents different validation checks. The possible values of this enumeration are isAlpha, isEmail, coef, avg, and age.

3. Syntax:

short form:

bool check(enum type Something, ...); // routine
check(isEmail, emailToCheck); // funcion call

full form:

#include "includes.h" //? The file wchich includes all required libraries to work.
// Here we used it to import stdarg.h library

enum type {isAlpha, isEmail, coef, avg, age};

bool check(enum type Something, ...) {
  va_list args;
  va_start(args, Something);

  char* str;
  int num;
  double moy;
  char *at;
  char *dot;

  switch(Something) {
    case isAlpha:
      str = va_arg(args, char*);
      for (int i = 0; i < strlen(str); i++) if (!isalpha(str[i])) return false;
      return true;
    break;

    case isEmail:
        str = va_arg(args, char*);
        at = strchr(str, '@');
        if (!at) {
            return false; //! '@' not found
        }
        dot = strchr(at, '.');
        return dot && dot > at; //! dot found and after '@'
    break;

    case coef:
      num = va_arg(args, int);
      return num > 0;
    break;

    case avg:
      moy = va_arg(args, double);
      return moy >= 0.0 && moy <= 20.0;
    break;

    case age:
      num = va_arg(args, int);
      return num >= 0 && num < 150;
    break;
  }

  va_end(args);
}

4. Defined Variables

Variable	Description
va_list args;	This variable is used to handle the variable arguments passed to the function.
char* str	It is a pointer to a character string used to store a string argument for validation.
int num	It is an integer variable used to store an integer argument for validation.
double moy	It is a double variable used to store a floating-point argument for validation.
char* at and char* dot	These variables are pointers to characters and are used for email validation.

5. Function Tasks:

Since it's a function which checks 5 types of inputs, we made a switch case to handle each type of inputs, dependes on enum type Something argument passed value

switch(Something) {
  case isAlpha:
    // Code for validating alphabetic string
    break;
  case isEmail:
    // Code for validating email
    break;
  case coef:
    // Code for validating coefficient
    break;
  case avg:
    // Code for validating average
    break;
  case age:
    // Code for validating age
    break;
}

5.1: Validation Check for Alphabetic String

case isAlpha:
    str = va_arg(args, char*);
    for (int i = 0; i < strlen(str); i++)
        if (!isalpha(str[i]))
            return false;
    return true;
break;

• This code block validates if the given string str consists only of alphabetic characters. It iterates over each character in the string and checks if it is an alphabet character using the isalpha function from(ctype.h).

• If any non-alphabetic character is found, the function returns false. Otherwise, if all characters are alphabetic, it returns true.

5.2: Validation Check for Email

case isEmail:    
    str = va_arg(args, char*);
    at = strchr(str, '@');
    if (!at) {
        return false; // '@' not found
    }
    dot = strchr(at, '.');
    return dot && dot > at; // dot found and after '@'
break;

• This code block validates if the given string str represents a valid email address. It checks if the string contains the '@' symbol followed by a dot ('.') character.

• It uses the strchr function (from string.h) to find the positions of the '@' and '.' characters in the string.

• If the '@' character is not found, the function returns false. Otherwise, it checks

5.3: Validation check for Coefficient values

case coef:
        num = va_arg(args, int);
        return num > 0;
break;

• This code block validates if the given integer value num represents a valid coefficient. It checks if the coefficient is greater than zero.

• If the coefficient is greater than zero, the function returns true. Otherwise, it returns false.

5.4: Validation check for Average values

case avg:
      moy = va_arg(args, double);
      return moy >= 0.0 && moy <= 20.0;
break;

• This code block validates if the given floating-point value moy represents a valid average. It checks if the average is between 0.0 and 20.0 (inclusive).

• If the average is within the valid range, the function returns true. Otherwise, it returns false.

5.5: Validation check for Age values

case age:
    num = va_arg(args, int);
    return num >= 0 && num < 150;
break;

• This code block validates if the given integer value num represents a valid age. It checks if the age is between 0 and 149 (inclusive).

• If the age is within the valid range, the function returns true. Otherwise, it returns false.