除去 logic, bit, byte, int, shortint, longint 等基本變數外，還有下列資料型別

（1） 字串 string

字串的宣告，大小，列印操作

module string_basic;
string dialog = "helloworld" ;
initial begin
	$display ("%s", dialog);
	$display("string name = %s", dialog);
  $display("string size = %0d",$size(dialog));
	foreach (dialog[i])
	begin
		$display("%s",dialog[i]);
	end
end 
endmodule
 

編譯結果

# Loading sv_std.std
# Loading work.string_basic(fast)
# 
# vsim -voptargs=+acc=npr
# run -all
# helloworld
# string name = helloworld
# string size = 10
# h
# e
# l
# l
# o
# w
# o
# r
# l
# d
# exit
# End time: 07:30:26 on Mar 29,2022, Elapsed time: 0:00:01
# Errors: 0, Warnings: 0
Done

字串可以比較、賦值

module string_operation;
	string firstname = "taylor" ;
	string lastname = "swift" ;
initial begin
	if (firstname == lastname)
		$display("firstname %s == lastname %s",firstname,lastname);
	else 
		$display("firstname %s != lastname %s",firstname,lastname);
	if (firstname <= lastname)
		$display("firstname %s <= lastname %s",firstname,lastname);
	else if (firstname >= lastname)
		$display("firstname %s >= lastname %s",firstname,lastname);
end
initial begin 
	$display("fullname is %s ",{firstname,lastname});
	$display("repeatname = %s",{3{firstname}});
	$display("firstname[2]=%s, lastname[2]=%s",firstname[2],lastname[2]);
  foreach(firstname[i]) begin
    $display("firstname[%0d]=%s",i,firstname[i]);
  end
end
endmodule
 

編譯結果

# Loading sv_std.std
# Loading work.string_operation(fast)
# 
# vsim -voptargs=+acc=npr
# run -all
# firstname taylor != lastname swift
# firstname taylor >= lastname swift
# fullname is taylorswift 
# repeatname = taylortaylortaylor
# firstname[2]=y, lastname[2]=i
# firstname[0]=t
# firstname[1]=a
# firstname[2]=y
# firstname[3]=l
# firstname[4]=o
# firstname[5]=r
# exit
# End time: 07:52:22 on Mar 29,2022, Elapsed time: 0:00:01
# Errors: 0, Warnings: 0
Done
 

通過編譯結果可以看出，字串的索引號是從左往右開始編號的，和佇列相似