Strings
Formal Definition
The strings are sequences of 8-bit ASCII characters enclosed within
quotation marks.
Simplified Syntax
"This is a string"
reg [8*number_of_characters:1]
string_variable;
Description
The string should be given in one line. Strings can contain special
characters (Example 1).
|
Character |
Meaning |
|
\n |
New line character |
|
\t |
Tab character |
|
\\ |
\ character |
|
\” |
" character |
|
\ddd |
A character specified by octal digit |
Table 24: Summary of special characters
String variables should be declared as reg type vectors (Example
2). Each character needs 8 bits.
If a string variable is used in an expression, it should be treated
as an unsigned value. If the size of a string assigned to a string
variable is smaller than the declared size of the variable, then it
will be left-padded with zeros.
The null string "” should be treated same as "\0”.
Concatenations of string variables preserve left-padded zeros of
these variables (Example 3).
Examples
Example 1
"\n This is the first line\n
This is the second line"
"\t Line\t with\t tab\t characters"
Example 2
reg [8*12:1] message;
The message variable can contain 12 characters.
Example 3
reg [10*8:1] s1, s2;
s1 = "Verilog";
s2 = "-HDL";
{s1, s2} <> {"Verilog", "-HDL"}
These expressions are not equal because {s1, s2} has 0s between
"Verilog” and "-HDL” and {"Verilog”,
"-HDL”} does not have any 0s between words.
Important Notes
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