Fortran 简明教程

Fortran - Decisions

决策结构要求程序员指定程序要评估或测试的一个或多个条件，以及在条件确定为 true 时要执行的语句或语句，另外还可选择在条件确定为 false 时要执行的其他语句。

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.

以下是大多数编程语言中常见的典型决策结构的一般形式 −

Following is the general form of a typical decision making structure found in most of the programming languages −

decision making

Fortran 提供以下类型的决策构建。

Fortran provides the following types of decision making constructs.

Sr.No

Statement & Description

1

If… then constructAn if… then… end if statement consists of a logical expression followed by one or more statements.

2

If… then…​else constructAn if… then statement can be followed by an optional else statement, which executes when the logical expression is false.

3

if…​else if…​else StatementAn if statement construct can have one or more optional else-if constructs. When the if condition fails, the immediately followed else-if is executed. When the else-if also fails, its successor else-if statement (if any) is executed, and so on.

4

nested if constructYou can use one if or else if statement inside another if or else if statement(s).

5

select case constructA select case statement allows a variable to be tested for equality against a list of values.

6

nested select case constructYou can use one select case statement inside another select case statement(s).