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Solaris Dynamic Tracing Guide
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Document Information

Preface

1.  Introduction

2.  Types, Operators, and Expressions

3.  Variables

4.  D Program Structure

5.  Pointers and Arrays

6.  Strings

String Representation

String Constants

String Assignment

String Conversion

String Comparison

7.  Structs and Unions

8.  Type and Constant Definitions

9.  Aggregations

10.  Actions and Subroutines

11.  Buffers and Buffering

12.  Output Formatting

13.  Speculative Tracing

14.  dtrace(1M) Utility

15.  Scripting

16.  Options and Tunables

17.  dtrace Provider

18.  lockstat Provider

19.  profile Provider

20.  fbt Provider

21.  syscall Provider

22.  sdt Provider

23.  sysinfo Provider

24.  vminfo Provider

25.  proc Provider

26.  sched Provider

27.  io Provider

28.  mib Provider

29.  fpuinfo Provider

30.  pid Provider

31.  plockstat Provider

32.  fasttrap Provider

33.  User Process Tracing

34.  Statically Defined Tracing for User Applications

35.  Security

36.  Anonymous Tracing

37.  Postmortem Tracing

38.  Performance Considerations

39.  Stability

40.  Translators

41.  Versioning

Glossary

Index

String Comparison

D overloads the binary relational operators and permits them to be used for string comparisons as well as integer comparisons. The relational operators perform string comparison whenever both operands are of type string, or when one operand is of type string and the other operand can be promoted to type string, as described in String Assignment. All of the relational operators can be used to compare strings:

Table 6-1 D Relational Operators for Strings

<
left-hand operand is less than right-operand
<=
left-hand operand is less than or equal to right-hand operand
>
left-hand operand is greater than right-hand operand
>=
left-hand operand is greater than or equal to right-hand operand
==
left-hand operand is equal to right-hand operand
!=
left-hand operand is not equal to right-hand operand

As with integers, each operator evaluates to a value of type int which is equal to one if the condition is true, or zero if it is false.

The relational operators compare the two input strings byte-by-byte, similar to the C library routine strcmp(3C). Each byte is compared using its corresponding integer value in the ASCII character set, as shown in ascii(5), until a null byte is read or the maximum string length is reached. Some example D string comparisons and their results are:

"coffee" < "espresso"
... returns 1 (true)
"coffee" == "coffee"
... returns 1 (true)
"coffee" >= "mocha"
... returns 0 (false)