“If语句”与“Switch语句”

Programming languages are a basic element in the digital era and programming itself is becoming more important everyday. The syntax of programming languages may vary significantly from each another, but there are some key factors and elements in each programming language that play a similar role. Programmers tend to make the best use of these key elements and factors to create a solution or complete a program. Conditional statements are one of these key elements in a programming language. ‘IF’ and ‘SWITCH’ are the conditional statements used by programming languages.

‘IF’ statement basis on the result and is used in nests as well depending on the requirement. ELSE is used in combination with IF statements to c***truct a complete statement or do a computation of more than one result. For example, a programmer may use an IF statement to confirm the gender of the user and the IF statement would only be run if the user entered the correct gender. The more appropriate way to assess this is to use both an IF and an ELSE statement where the user enters his/her choice and even if the IF statement is not correct, the second choice can be executed with the use of ELSE. The IF statement is most suitable where there are limited comparis*** to be made. IF statements tend to be lengthy since the whole logical expression needs to be typed each time in a program with lots of comparis***.

The ‘SWITCH’ statement is also a conditional statement used in programming languages for logical and conditional computing. SWITCH uses CASE and DEFAULT within its structure to perform a conditional task. The SWITCH statement is preferred in cases where there is a lengthy list that needs to be compared with the variable. It is also the preferred conditional statement used by the programmers with its easy flow and efficient proofreading aspect. Further to this, the SWITCH statement is used in a way that it evaluates the condition with the list of cases available and then executes the case that has the correct value. The gender confirmation example stated above can also be evaluated through SWITCH statement in a very similar way using appropriate SWITCH procedure. Summary:

1. SWITCH statement is easier to express for lengthy conditi*** when compared to an IF statement which gets more complex as the number of conditi*** grow and the nested IF comes into play.

2. SWITCH statement allows easy proofreading while testing and removing bugs from the source code whereas IF statement makes 编辑difficult.

3. Expression is evaluated and SWITCH statement is run according to the result of the expression that can be integer or logical while IF statement is run only if the result of the expression is true.

4. SWITCH allows expression to have integer based evaluation while IF statement allows both integer and character based evaluation.

5. SWITCH statement can be executed with all cases if the ‘break’ statement is not used whereas IF statement has to be true to be executed further.