In this posting I want explain about structure and statement in programming. The most common type of instruction in a program is the statement. A statement in C++ is the smallest independent unit in the language. In human language, it is analogous to a sentence. We write sentences in order to convey an idea. In C++, we write statements in order to convey to the compiler that we want to perform a task. Statements in C++ are terminated by a semicolon.
There are many different kinds of statements in C++. The following are some of the most common types of simple statements:
#include <iostream>
int main()
{
using namespace std;
cout << "Hello world!" << endl;
return 0;
}
int x is a declaration statement. It tells the compiler that x is a variable. All variables in a program must be declared before they are used. We will talk more about variables shortly.
x = 5 is an assignment statement. It assigns a value (5) to a variable (x).
cout << x; is an output statement. It outputs the value of x (which we set to 5 in the previous statement) to the screen.
The compiler is also capable of resolving expressions. An expression is an mathematical entity that evaluates to a value. For example, in math, the expression 2+3 evaluates to the value 5. Expressions can involve values (such as 2), variables (such as x), operators (such as +) and functions (which return an output value based on some input value). They can be singular (such as 2, or x), or compound (such as 2+3, 2+x, x+y, or (2+x)*(y-3)).
For example, the statement x = 2 + 3; is a valid assignment statement. The expression 2+3 evaluates to the value of 5. This value of 5 is then assigned to x.
What is the difference between a statement and an expression? A statement is a “complete sentence” that tells the compiler to perform a particular task. An expression is a mathematical entity that evaluates to a value. Expressions are often used inside of statements. What symbol do statements in C++ end with? The semicolon (;)
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