一、枚举类型转化

将1转换成枚举类型st2 = state_t'(1)，可以成功转换。
将4转换成枚举类型st2 = state_t'(4); 超出范围，不可以转换成枚举类型，但是st1 value = 4且不报错。可以用if(!$cast(st2,4)) $error来判定。

initial begin: enum_typetypedef enum {IDLE, START, PROC, END} state_t;state_t st1, st2;wait(b_enum_type == 1); $display("enum_type process block started");st1 = IDLE;$display("st1 value = %0d (int)", st1);$display("st1 value = %s (string)", st1); // implicit conversion$display("st1 value = %s (string)", st1.name());st2 = state_t'(1); $display("st1 value = %0d (int)", st2);$display("st1 value = %s (string)", st2.name());st2 = state_t'(4); if(!$cast(st2,4))$error("int 4 to state_t conversion failure")$display("st1 value = %0d (int)", st2);$display("st1 value = %s (string)", st2.name());
end

# enum_type process block started
# st1 value = 0 (int)
# st1 value = IDLE (string)
# st1 value = IDLE (string)
# st1 value = 1 (int)
# st1 value = START (string)

#int 4 to state_t conversion failure

# st1 value = 4(int)
# st1 value = (string)

二、结构体

创建结构体、声明变量、初始化变量（注意单引号）
结构体默认为非组合类型，需要单引号在定义的时候达到非组合赋值给非组合类型
%p可用于打印聚合表达式，默认打印10进制。

initial begin: struct_typetypedef struct {bit[7:0] addr;bit[31:0] data;bit is_write;int id;} trans_t;             //创建结构体trans_t t1, t2, t3;    //声明变量wait(b_struct_type == 1); $display("struct_type process block started");t1 = '{'h10, 'h1122_3344, 'b1, 'h1000};   //初始化$display("t1 data content is %p", t1);t2.addr = 'h20;t2.data = 'h5566_7788;t2.is_write = 'b0;t2.id = 'h2000;$display("t2 data content is %p", t2);t3 = t2;t3.data = 'h99AA_BBCC;t3.id = 'h3000;$display("t3 data content is %p", t3);$display("t2 data content is %p", t2);
end

# struct_type process block started
# t1 data content is '{addr:16, data:287454020, is_write:1, id:4096}
# t2 data content is '{addr:32, data:1432778632, is_write:0, id:8192}
# t3 data content is '{addr:32, data:2578103244, is_write:0, id:12288}
# t2 data content is '{addr:32, data:1432778632, is_write:0, id:8192}

不加单引号，定义组合类型的数组，赋值给组合类型（packed）。此时trans_t是 bit[72:0],t1也是72位数组组合赋值。

 typedef struct packed {bit[7:0] addr;bit[31:0] data;bit is_write;int id;} trans_t;             //创建结构体trans_t t1, t2, t3;    //声明变量wait(b_struct_type == 1); $display("struct_type process block started");t1 = {8'h10, 32'h1122_3344, 1'b1, 32'h1000};   //初始化

三、合并数组和非合并数组

1、非组合型

框图表示储存方式，从上到下表示0、1、2、3
代码中可以进行单个空间赋值，也可以用 '{} 的形式进行非组合赋值

  bit [7:0] unpacked_word [3:0];unpacked_word[0] = 10;unpacked_word[1] = 32;unpacked_word[2] = 54;unpacked_word[3] = 76;$display("unpacked_word = %p", unpacked_word);// legal assignment with '{}unpacked_word = '{76, 54, 32, 10};$display("unpacked_word = %p", unpacked_word);

2、组合型

框图表示储存方式，从左到右表示3、2、1、0
代码中同样可以进行单个空间赋值，或者不加单引号，内部声明数据类型进行组合赋值，注意如果不声明数据位数，则每个数据默认32位，packed_word为128位，但是只保存低32位。
利用左移符时不声明数据位数，因为声明之后左移会使其消失。

  // legal assignmentpacked_word[0] = 10;packed_word[1] = 32;packed_word[2] = 54;packed_word[3] = 76;$display("packed_word = %p", packed_word);// legal assignment with {} but without 'packed_word = {8'd76, 8'd54, 8'd32, 8'd10};packed_word = (76<<24) + (54<<16) + (32<<8) + 10;

3、数组中数据查找

//四行，每行两个8位数据，赋值方式如下。
integer sum [4][2]; // 8*4 size array sum = '{0:'{'h21, 'h43}, default:'{default:'x}};//零行有两个数据，非组合，剩余定义为 'x//两种数值查找方式 
foreach(sum[i, j]) begin$display("sum[%0d][%0d] = 'h%0x", i, j, sum[i][j]);
endforeach(sum[m]) beginforeach(sum[m][n]) begin$display("sum[%0d][%0d] = 'h%0x", m, n, sum[m][n]);endend

注意：sum [4][2]中sum [0][0]为'h21，如果是sum [3:0][1:0]排列，sum [0][0]为'h43

四、字符串string

创建字符串、初始化
连接字符串的两种方式1、大括号{str , s2}; 2、s4 = $sformatf("%s to %s", s1, s2);
$sformatf作用是整理字符串格式。

initial begin: string_formatstring s1, s2, s3, s4;wait(b_string_format == 1);$display("string_format process block started");s1 = "Welcome";s2 = "www.rockeric.com";s3 = {s1, " to ", s2}; // concatenation operator '{...}'$display("s3 content: %s", s3);s4 = $sformatf("%s to %s", s1, s2); // system format function$display("s4 content: %s", s4);
end

# string_format process block started
# s3 content: Welcome to www.rockeric.com
# s4 content: Welcome to www.rockeric.com

五、关联数组

id_score1[int]中的int（也可以用其他的类型）作为index的类型，不需要连续。

int id_score1[int], id_score2[int]; // key ID, value SCOREid_score1[101] = 111;id_score1[102] = 222;id_score1[103] = 333;id_score1[104] = 444;id_score1[105] = 555;id_score2 = id_score1;id_score2[101] = 101;id_score2[112] = 102;id_score2[123] = 103;

注意：id_score2[101] = 101;为修改关联数组的值，id_score2[112] = 102;id_score2[123] = 103;为新添加到关联数组的值。