Fortran 字符

Fortran 语言可以将字符视为单个字符或连续字符串。

字符可以是从基本字符集中提取的任何符号，即从字母、十进制数字、下划线和21个特殊字符中提取的符号。

字符常数是一个固定值的字符串。

内部数据类型字符存储字符和字符串。字符串的长度可以通过 len 说明符指定。如果没有指定长度，则为 1。您可以按位置引用字符串中的单个字符；最左侧的字符位于位置 1。

字符声明

声明字符类型数据与其他变量相同：

type-specifier :: variable_name

比如：

character :: reply, sex

可以这样赋值：

reply = 'N'
sex = 'F'

下面的实例演示了字符数据类型的声明和使用：

program hello
implicit none
   character(len = 15) :: surname, firstname
   character(len = 6) :: title
   character(len = 25)::greetings
   title = 'Mr. '
   firstname = 'Rowan '
   surname = 'Atkinson'
   greetings = 'A big hello from Mr. Bean'
   print *, 'Here is ', title, firstname, surname
   print *, greetings
end program hello

结果如下：

Here is Mr. Rowan Atkinson
A big hello from Mr. Bean

连接字符串

连接运算符 // 用于连接字符。

以下实例演示了这一点：

program hello
implicit none
   character(len = 15) :: surname, firstname
   character(len = 6) :: title
   character(len = 40):: name
   character(len = 25)::greetings
   title = 'Mr. '
   firstname = 'Rowan '
   surname = 'Atkinson'
   name = title//firstname//surname
   greetings = 'A big hello from Mr. Bean'
   print *, 'Here is ', name
   print *, greetings
end program hello

结果为：

Here is Mr.Rowan Atkinson
A big hello from Mr.Bean

一些字符函数

下表显示了一些常用的字符函数及其说明：

实例 1

此实例显示了 index 函数的使用：

program testingChars
implicit none
   character (80) :: text
   integer :: i
   text = 'The intrinsic data type character stores characters and   strings.'
   i=index(text,'character')
   if (i /= 0) then
      print *, ' The word character found at position ',i 
      print *, ' in text: ', text
   end if
end program testingChars

结果为：

The word character found at position 25
in text : The intrinsic data type character stores characters and strings.

实例 2

此实例演示了 trim 功能的使用：

program hello
implicit none
   character(len = 15) :: surname, firstname
   character(len = 6) :: title
   character(len = 25)::greetings
   title = 'Mr.'
   firstname = 'Rowan'
   surname = 'Atkinson'
   print *, 'Here is', title, firstname, surname
   print *, 'Here is', trim(title),' ',trim(firstname),' ', trim(surname)
end program hello、

结果为：

Here isMr.   Rowan          Atkinson
Here isMr. Rowan Atkinson

实例 3

此实例演示了 achar 功能的使用：

program testingChars
implicit none
   character:: ch
   integer:: i
   do i = 65, 90
      ch = achar(i)
      print*, i, ' ', ch
   end do
end program testingChars

结果为：

65  A
66  B
67  C
68  D
69  E
70  F
71  G
72  H
73  I
74  J
75  K
76  L
77  M
78  N
79  O
80  P
81  Q
82  R
83  S
84  T
85  U
86  V
87  W
88  X
89  Y
90  Z

检查字符的顺序

以下函数确定字符的顺序：

实例 4

以下函数演示了使用方法：

program testingChars
implicit none
   character:: a, b, c
   a = 'A'
   b = 'a'
   c = 'B'
   if(lgt(a,b)) then
      print *, 'A is lexically greater than a'
   else
      print *, 'a is lexically greater than A'
   end if
   if(lgt(a,c)) then
      print *, 'A is lexically greater than B'
   else
      print *, 'B is lexically greater than A'
   end if
   if(llt(a,b)) then
      print *, 'A is lexically less than a'
   end if
   if(llt(a,c)) then
      print *, 'A is lexically less than B'
   end if
end program testingChars

结果为：

a is lexically greater than A
B is lexically greater than A
A is lexically less than a
A is lexically less than B