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Learn to Code: C++ for Absolute Beginners

Fundamentals of C++

Explore fundamental C++ concepts including common data types such as int, double, bool, char, and string. Understand variable declaration, initialization to avoid garbage values, and using key operators like arithmetic, comparison, and logical. Learn to perform math functions like power and square root with C++ math library support.

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Data types in C++

Every variable in C++ needs to be declared with the help of a data type. For example, whether a variable can store only numbers or can also store other symbols as its value.

Common data types

The following are the commonly used data types in C++:

  • int: Integer values (5, 0, -1, etc.)

  • double: Floating-point values (2.33333, -2500.001, 20.0, etc.)

  • bool: Boolean values (true/1, false/0)

  • char: Character value (a, 0, ＄, etc)

  • string: String values (educative, c++, k2, etc.)

The bool data type is used to store true or false, but whenever we display the Boolean values, true is displayed as 1 and false as 0. In order to use the string data type, we have to add #include <string> at the start of the code.

Variable declaration

The C++ language requires the programmer to tell the data type of the variables used in a program. The following code demonstrates the declaration of variables to input their values with a suitable prompt and to display them with suitable labels:

#include <iostream>
#include <string>
using namespace std;

int main()
{
   string str; // Declaring a variable of type string
   int number; // Declaring a variable of type integer
   double real; // Declaring a variable of type double
   bool isTrue; // Declaring a variable of type bool
   char letter; // Declaring a variable of type char

   cout << "Please input a word: ";
   cin >> str;
   cout << "Please input an integer: ";
   cin >> number;
   cout << "Please input a real number: ";
   cin >> real;
   cout << "Please input 0 or 1 [0 for false, 1 for true]: ";
   cin >> isTrue;
   cout << "Please input a letter: ";
   cin >> letter;
   cout << "The value of each variable is enclosed in brackets:" << std::endl;
   cout << "str (" << str << ")" << endl;
   cout << "number (" << number << ")" << endl;
   cout << "real number (" << real << ")" << endl;
   cout << "isTrue (" << isTrue << ")" << endl;
   cout << "letter (" << letter << ")" << endl;
   return 0;
}
Variable declaration

Note: We don’t use < and > with string other than #include because it’s a data type. The string at line 2 is the name of the file that defines the string data type.

Explanation

  • Line 7–11: We declare the variables so they can be used to store the values input by the user. There are different types of variables that are declared:
    • str is a variable of the string type.
    • number is a variable of the int type.
    • fraction is a variable of the double type.
    • isTrue is a variable of the bool type.
    • letter is a variable of the char type.
  • Line 13–22: We output a prompt using cout and demand input from the user using cin and
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