C++ Files and Streams
So far, we have been using the iostream standard library, which provides cin and cout methods for reading from standard input and writing to standard output respectively.
This tutorial will teach you how to read and write from a file. This requires another standard C++ library called fstream, which defines three new data types −
C++ provides following two types of string representations −
• The C-style character string.
• The string class type introduced with Standard C++.
C++ provides a data structure, the array, which stores a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.
Instead of declaring individual variables, such as number0, number1, ..., and number99, you declare one array variable such as numbers and use numbers[0], numbers[1], and ..., numbers[99] to represent individual variables. A specific element in an array is accessed by an index.
Normally, when we work with Numbers, we use primitive data types such as int, short, long, float and double, etc. The number data types, their possible values and number ranges have been explained while discussing C++ Data Types.
A function is a group of statements that together perform a task. Every C++ program has at least one function, which is main(), and all the most trivial programs can define additional functions.
You can divide up your code into separate functions. How you divide up your code among different functions is up to you, but logically the division usually is such that each function performs a specific task.
A function declaration tells the compiler about a function's name, return type, and parameters. A function definition provides the actual body of the function.
There may be a situation, when you need to execute a block of code several number of times. In general, statements are executed sequentially: The first statement in a function is executed first, followed by the second, and so on.
Programming languages provide various control structures that allow for more complicated execution paths.
A loop statement allows us to execute a statement or group of statements multiple times and following is the general from of a loop statement in most of the programming languages
An if statement consists of a boolean expression followed by one or more statements.
An operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations. C++ is rich in built-in operators and provide the following types of operators −
• Arithmetic Operators
• Relational Operators
• Logical Operators
• Bitwise Operators
• Assignment Operators
• Misc Operators
This chapter will examine the arithmetic, relational, logical, bitwise, assignment and other operators one by one.
Constants refer to fixed values that the program may not alter and they are called literals.
Constants can be of any of the basic data types and can be divided into Integer Numerals, Floating-Point Numerals, Characters, Strings and Boolean Values.
Again, constants are treated just like regular variables except that their values cannot be modified after their definition.
A scope is a region of the program and broadly speaking there are three places, where variables can be declared −
• Inside a function or a block which is called local variables,
• In the definition of function parameters which is called formal parameters.
• Outside of all functions which is called global variables.
We will learn what is a function and it's parameter in subsequent chapters. Here let us explain what are local and global variables.