Simple Program for Student C++
Control Structures |
| |A program is usually not limited to a linear sequence of instructions. During its process it may bifurcate, repeat code or take decisions. For that purpose, C++ provides control structures that serve to specify what has to be done by our program, when and under which circumstances.
With the introduction of control structures we are going to have to introduce a new concept: the compound-statement or block. A block is a group of statements which are separated by semicolons (;) like all C++ statements, but grouped together in a block enclosed in braces: { }:
{ statement1; statement2; statement3; }
Most of the control structures that we will see in this section require a generic statement as part of its syntax. A statement can be either a simple statement (a simple instruction ending with a semicolon) or a compound statement (several instructions grouped in a block), like the one just described. In the case that we want the statement to be a simple statement, we do not need to enclose it in braces ({}). But in the case that we want the statement to be a compound statement it must be enclosed between braces ({}), forming a block.
Conditional structure: if and else
The if keyword is used to execute a statement or block only if a condition is fulfilled. Its form is: if (condition) statement
Where condition is the expression that is being evaluated. If this condition is true, statement is executed. If it is false, statement is ignored (not executed) and the program continues right after this conditional structure.
For example, the following code fragment prints x is 100 only if the value stored in the x variable is indeed 100:
|if (x == 100) |
| |A program is usually not limited to a linear sequence of instructions. During its process it may bifurcate, repeat code or take decisions. For that purpose, C++ provides control structures that serve to specify what has to be done by our program, when and under which circumstances.
With the introduction of control structures we are going to have to introduce a new concept: the compound-statement or block. A block is a group of statements which are separated by semicolons (;) like all C++ statements, but grouped together in a block enclosed in braces: { }:
{ statement1; statement2; statement3; }
Most of the control structures that we will see in this section require a generic statement as part of its syntax. A statement can be either a simple statement (a simple instruction ending with a semicolon) or a compound statement (several instructions grouped in a block), like the one just described. In the case that we want the statement to be a simple statement, we do not need to enclose it in braces ({}). But in the case that we want the statement to be a compound statement it must be enclosed between braces ({}), forming a block.
Conditional structure: if and else
The if keyword is used to execute a statement or block only if a condition is fulfilled. Its form is: if (condition) statement
Where condition is the expression that is being evaluated. If this condition is true, statement is executed. If it is false, statement is ignored (not executed) and the program continues right after this conditional structure.
For example, the following code fragment prints x is 100 only if the value stored in the x variable is indeed 100:
|if (x == 100) |