Difference between revisions of "PLC Laboratory 2"
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The input may be containing the following symbols: | The input may be containing the following symbols: | ||
* ''identifiers'' - consisting of a sequence of letters and numbers starting with a letter | * ''identifiers'' - consisting of a sequence of letters and numbers starting with a letter | ||
| − | * numbers - formed by a sequence of decimal digits | + | * ''numbers'' - formed by a sequence of decimal digits |
| − | * operators - symbols '+', '-', '*' and '/', | + | * ''operators'' - symbols <code>'+', '-', '*' and '/'</code>, |
| − | * delimiters - symbols '(', ')' and ';', | + | * ''delimiters'' - symbols <code>'(', ')' and ';'</code>, |
| − | * keywords - <code>div</code> and <code>mod</code>. | + | * ''keywords'' - <code>div</code> and <code>mod</code>. |
Symbols can be separated by a sequence of spaces, tabs, and line breaks. | Symbols can be separated by a sequence of spaces, tabs, and line breaks. | ||
Notes are preceded by a sequence <code>//</code> and continue to the end of the line. | Notes are preceded by a sequence <code>//</code> and continue to the end of the line. | ||
| − | |||
== Output specification == | == Output specification == | ||
Revision as of 08:34, 26 January 2022
Lexical analyzer
Write a program, that reads an input and converts it into a sequence of lexical symbols – tokens. Each token composes from a type and possibly a value.
The tokens definition depends on you, and it is considered a part of the solution.
Input specification
The input may be containing the following symbols:
- identifiers - consisting of a sequence of letters and numbers starting with a letter
- numbers - formed by a sequence of decimal digits
- operators - symbols
'+', '-', '*' and '/', - delimiters - symbols
'(', ')' and ';', - keywords -
divandmod.
Symbols can be separated by a sequence of spaces, tabs, and line breaks.
Notes are preceded by a sequence // and continue to the end of the line.
Output specification
For each expression write one line containing the result – the computed value of the expression. If there is any error in the input, write text ERROR instead.
Example
- Input
2
2 * (3+5)
15 - 2**7
- Output
16
ERROR
