Decision Making in C or C++ with examples

Decision making is one of the most important concepts of computer programming. As the name suggests “Decision Making” , we means to state that we will be making certain decisions to carry out different operations. These decisions making strategies are same as we come across in our daily life. But here we will be using these decision making strategies by using syntax and semantics provided by the language.

In this, programs should be able to make logical (true/false) decisions based on the condition they are in. Every program has one or few problems to solve, depending on the nature of the problems, important decisions have to be made in order to solve those particular problems. Decision making structures require that the programmer specify one or more conditions to be evaluated or tested by the program, along with a statement or statements to be executed if the condition is determined to be true, and optionally, other statements to be executed if the condition is determined to be false.

decision_making

Following is the general from of a typical decision making structure found in most of the programming languages:

C programming language assumes any non-zero and non-null values as true and if it is either zero or null then it is assumed as false value.

C programming language provides following types of decision making statements.

Statement

Description

if statement An if statement consists of a boolean expression followed by one or more statements.
if…else statement An if statement can be followed by an optional else statement, which executes when the boolean expression is false.
nested if statements You can use one if or else if statement inside another if or else if statement(s).
switch statement A switch statement allows a variable to be tested for equality against a list of values.
nested switch statements You can use one swicth statement inside another switch statement(s).

The ? : Operator:

We have covered conditional operator ? : in previous chapter which can be used to replace if…else statements. It has the following general form:

Exp1 ? Exp2 : Exp3;

Where Exp1, Exp2, and Exp3 are expressions. Notice the use and placement of the colon.

The value of a ? expression is determined like this: Exp1 is evaluated. If it is true, then Exp2 is evaluated and becomes the value of the entire ? expression. If Exp1 is false, then Exp3 is evaluated and its value becomes the value of the expression.