Sas 简明教程

SAS - Strings

在 SAS 中，字符串是包含在一对单引号中的值。还需要在变量声明的末尾添加一个空格和 $ 符号，才能声明字符串变量。SAS 具有很多可以分析和操作字符串的强大函数。

Strings in SAS are the values which are enclosed with in a pair of single quotes. Also the string variables are declared by adding a space and $ sign at the end of the variable declaration. SAS has many powerful functions to analyze and manipulate strings.

Declaring String Variables

我们可以声明字符串变量及其值，如下所示。在下面的代码中，我们声明了两个长度分别为 6 和 5 的字符变量。LENGTH 关键字用于声明变量而不创建多个观测值。

We can declare the string variables and their values as shown below. In the code below we declare two character variables of lengths 6 and 5. The LENGTH keyword is used for declaring variables without creating multiple observations.

data string_examples;
   LENGTH string1 $ 6 String2 $ 5;
   /*String variables of length 6 and 5 */
   String1 = 'Hello';
   String2 = 'World';
   Joined_strings =  String1 ||String2 ;
run;
proc print data = string_examples noobs;
run;

在运行上述代码后，我们得到了一个输出，其中显示了变量名及其值。

On running the above code we get the output which shows the variable names and their values.

strings 1 concatenate

String Functions

以下是经常使用的一些 SAS 函数的示例。

Below are the examples of some SAS functions which are used frequently.

SUBSTRN

此函数使用起始和结束位置提取子字符串。如果未提及结束位置，它将一直提取到字符串的末尾。

This function extracts a substring using the start and end positions. In case of no end position is mentioned it extracts all the characters till end of the string.

Syntax

SUBSTRN('stringval',p1,p2)

以下是所用参数的描述 -

Following is the description of the parameters used −

  1. stringval is the value of the string variable.

  2. p1 is the start position of extraction.

  3. p2 is the final position of extraction.

Example

data string_examples;
   LENGTH string1 $ 6 ;
   String1 = 'Hello';
   sub_string1 = substrn(String1,2,4) ;
   /*Extract from position 2 to 4 */
   sub_string2 = substrn(String1,3) ;
   /*Extract from position 3 onwards */
run;
proc print data = string_examples noobs;
run;

在运行上述代码后，我们得到了一个显示 substrn 函数结果的输出。

On running the above code we get the output which shows the result of substrn function.

strings 2 substr

TRIMN

此函数删除字符串中的结尾空格。

This function removes the trailing space form a string.

Syntax

TRIMN('stringval')

以下是所用参数的描述 -

Following is the description of the parameters used −

  1. stringval is the value of the string variable.

data string_examples;
   LENGTH string1 $ 7  ;
   String1='Hello  ';
   length_string1 = lengthc(String1);
   length_trimmed_string = lengthc(TRIMN(String1));
run;
proc print data = string_examples noobs;
run;

在运行上述代码后，我们得到了一个显示 TRIMN 函数结果的输出。

On running the above code we get the output which shows the result of TRIMN function.

strings 3 trimn