Organisation within Menu calculator-CodePudding

#include <iostream>
#include <regex>

using namespace std;

void main_menu();
int get_user_input();
void select_menu_item(int input);
void print_main_menu();
void go_back_to_main_menu();
bool is_integer(std::string num);
void menu_item_1();
void menu_item_2();
void menu_item_3();
void menu_item_4();

int main(int argc, char const *argv[]) {
  //int num1, num2, choice, i;
  main_menu();
  return 0;
}

void main_menu() {
  char fav;
 int num1,num2,choice,i;
 cout<<"\n Enter 1st Number: ";
 cin>>num1;
 cout<<"\n Enter 2nd Number: ";
 cin>>num2;
  print_main_menu();
  int input = get_user_input();
  select_menu_item(input);
  //void menu_item_1(); 
}


int get_user_input() {
  int input;
  std::string input_string;
  bool valid_input = false;
  int menu_items = 5;

  do {
    std::cout << "\nSelect item: ";
    std::cin >> input_string;
    valid_input = is_integer(input_string);
    // if input is not an integer, print an error message
    if (valid_input == false) {
      std::cout << "Enter an integer!\n";
    } else {  // if it is an int, check whether in range
      input = std::stoi(input_string);  // convert to int
      if (input >= 1 && input <= menu_items) {
        valid_input = true;
      } else {
        std::cout << "Invalid menu item!\n";
        valid_input = false;
      }
    }
  } while (valid_input == false);

  return input;
}

void select_menu_item(int input) {
  switch (input) {
    case 1:
      menu_item_1();
       break;
    case 2:
      menu_item_2();
      break;
    case 3:
      menu_item_3();
      break;
    case 4:
      menu_item_4();
      break;
    default:
      exit(1);
      break;
  }
}

void print_main_menu() {
  
  std::cout << "\n----------- Main menu -----------\n";
  std::cout << "|\t\t\t\t\t\t|\n";
  std::cout << "|\t1. Menu item 1\t\t|\n";
  std::cout << "|\t2. Menu item 2\t\t|\n";
  std::cout << "|\t3. Menu item 3\t\t|\n";
  std::cout << "|\t4. Menu item 4\t\t|\n";
  std::cout << "|\t5. Exit\t\t\t\t|\n";
  std::cout << "|\t\t\t\t\t\t|\n";
  std::cout << "---------------------------------\n";
}

void go_back_to_main() {
  std::string input;
  do {
    std::cout << "\nEnter 'b' or 'B' to go back to main menu: ";
    std::cin >> input;
  } while (input != "b" && input != "B");
  main_menu();
}

// https://codereview.stackexchange.com/questions/162569/checking-if-each-char-in-a-string-is-a-decimal-digit
bool is_integer(std::string num) {
  return std::regex_match(num, std::regex("[ -]?[0-9] "));
}

void menu_item_1() {
  
  int num1, num2, choice, i;
  std::cout << "\n>> Menu 1\n";
  std::cout << "\n Sum of "<< num1 <<" and "<< num2;
            cout << " = "<<num1 num2;
  //std::cin>> Menu_item 1;         
  // you can call a function from here that handles menu 1
  go_back_to_main();
}
void menu_item_2() {
  std::cout << "\n>> Menu 2\n";
  std::cout << "\nSome code here does something useful\n";
  // you can call a function from here that handles menu 2
  go_back_to_main();
}
void menu_item_3() {
  std::cout << "\n>> Menu 3\n";
  std::cout << "\nSome code here does something useful\n";
  // you can call a function from here that handles menu 3
  go_back_to_main();
}
void menu_item_4() {
  std::cout << "\n>> Menu 4\n";
  std::cout << "\nSome code here does something useful\n";
  // you can call a function from here that handles menu 4
  go_back_to_main();
}

output:

Enter 1st Number: 56

 Enter 2nd Number: 87

----------- Main menu -----------
|                       |
|   1. Menu item 1      |
|   2. Menu item 2      |
|   3. Menu item 3      |
|   4. Menu item 4      |
|   5. Exit             |
|                       |
---------------------------------

Select item: 1

>> Menu 1

 Sum of 0 and 6596224 = 6596224
Enter 'b' or 'B' to go back to main menu:

I feel I am close to getting the first menu function working however I can't work out why the output for Menu 1 keeps returning "Sum of 0 and 6596224 = 6596224". I am not sure which part of the code needs rearranging.

I am aware I have only completed the addition but once I have figured out what is going wrong here I'm sure I will be able to complete the rest of it.

Thanks

CodePudding user response：

num1 in main and num1 in menu_item_1() are two completely unrelated variables. Same for num2. Both are not initialized in menu_item_1.

If you already read the values before, you can pass them to the function:

void menu_item_1(int num1, int num2) {
  std::cout << "\n>> Menu 1\n";
  std::cout << "\n Sum of " << num1 << " and " << num2;
  std::cout << " = " << num1 num2;
}

I do not understand the purpose of go_back_to_main, because it keeps the user in an infinite loop and the only choice they have is to confirm by typing either 'b' or 'B', hence I removed it.

CodePudding user response：

Use of uninitialized variables is similar to use of uninitialized memory and might be a source of errors of different kinds to occur during program execution.

Like the previous solution, you need values entered by the user to the functions menu_item_ *.

void menu_item_1() {
  int num1, num2, choice, i;
  cin >> num1 >> num2;
  cout << ">> Menu 1\n Sum of " << num1 << "and " << num2 << " = " << num1 num2 << endl;
  go_back_to_main();
}

output:


 Enter 1st Number: 1

 Enter 2nd Number: 1

----------- Main menu -----------
|                       |
|   1. Menu item 1      |
|   2. Menu item 2      |
|   3. Menu item 3      |
|   4. Menu item 4      |
|   5. Exit             |
|                       |
---------------------------------

Select item: 1
Enter number 1 and number 2 
4512 4123
>> Menu 1
 Sum of 4512 and 4123 = 8635

Enter 'b' or 'B' to go back to main menu:

run here