Introduction to basic syntax in C++

Structure of a C++ program

Every C++ program consists of the following components:

• Header files: These contain declarations of functions, variables, and constants that are used in the program. To include a header file, use the #include preprocessor directive, followed by the name of the header file enclosed in angle brackets (<>) or quotes ("").

  Note: Quotes are used for the headers you create, for STL (Standard Library), you should always use brackets.

    #include <iostream>
    #include "my_header_file.h"
  

• Main function: The main function is the entry point of a C++ program. The operating system calls this function when the program starts. The main function has the following signature:

    int main() {
        // Your code goes here
        return 0;
    }
  

• Statements: C++ programs consist of a sequence of statements that are executed in order. Statements are typically terminated with a semicolon (;).

Variable declarations

In C++, variables must be declared before they can be used. A variable declaration includes the data type, variable name, and an optional initializer. For example:

int x; // Declare an integer variable named x
float y = 3.14; // Declare a float variable named y and initialize it with the value 3.14

There are also many other types like:

• Double (a float with twice the byte size (8).)

• Char

• Wchar_t (Wide char, holds 2 bytes instead of one.)

• Boolean

• Void

There are also many type modifiers (signed, unsigned, etc...) that we will see later on.

Conditional statements

Conditional statements allow you to execute different parts of your code based on certain conditions. The most common conditional statements are if, if-else, and switch. Here's an example of an if-else statement:

int age = 18;

if (age >= 18) {
    std::cout << "You are an adult." << std::endl;
} else {
    std::cout << "You are a minor." << std::endl;
}

Note that you can also use switch for conditions by using the following syntax:

int age = 18;

switch(age){
    case (18):
        std::cout << "You are an adult." << std::endl;
        break;
    case (15):
        std::cout << "You are a minor." << std::endl;
        break;
    default:
        std::cout << "I don't know this number." << std::endl;
        break;
}

For the switch, only recognized cases will be handled, the default case is for unhandled cases.

Loops

Loops are used to execute a block of code repeatedly until a specified condition is met. C++ supports three types of loops: for, while, and do-while. Here's an example of a for loop:

for (int i = 0; i < 10; i++) {
    std::cout << "i is " << i << std::endl;
}

In C++11, a new type of loop was introduced, the range-based loop that is suited to view the contents of an array or a vector for example:

#include <vector> //This statement is needed to use vector

std::vector<int> numbers = { 1, 2, 3, 4, 5 };
for (int number : numbers) {
    std::cout << "Number is " << number << std::endl;
}

Conclusion

Understanding the basic syntax of C++ is the first step in learning the language. In this article, we covered the structure of a C++ program, variable declarations, conditional statements, and loops. In future articles, we will dive deeper into other important concepts like functions, pointers, and object-oriented programming.