Python 2.7.3 如果将变量与字符串进行比较

Question

import serial
import MySQLdb

dbConn = MySQLdb.connect("localhost","root","test","ISEF_DB") or die ("Could not connect to database")
cursor = dbConn.cursor()

device = '/dev/ttyACM0'

try:
    print "Trying...",device
    arduino = serial.Serial(device, 250000)
except:
    print "Failed to connect on",device

try:
    data = arduino.readline() #read data
#   pieces = data.split("\t")
    print "The data is:",data
    if data == 461518B1:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '461518B1'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    elif data == 46154D41:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '46154D41'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    elif data == 4615A161:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '4615A161'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    elif data == 4616A511:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '4616A511'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    elif data == 46193031:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '46193031'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    elif data == 46196771:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '46196771'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    elif data == 461A79D1:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '461A79D1'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    elif data == 46211881:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '46211881'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    elif data == 465598F1:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '465598F1'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    elif data == 9A2DCDE4:
        try:
            cursor.execute("UPDATE `ISEF_DB`.`attendance` SET `present`='1' WHERE `id` = '9A2DCDE4'")
            dbConn.commit()
            cursor.close()
            print "data inserted"
        except MySQLdb.IntegrityError:
            print "Failed to insert data"
        finally:
            cursor.close()
            print "done"
    else:
        print "Card not recognized"

except:
    print "Failed to get data"

这段代码给了我以下错误

  File "test.py", line 19
    if 461518B1 == data:
              ^
SyntaxError: invalid syntax

我想要做的是将变量与字符串进行比较，但它不起作用。我看不出我做错了什么。数据值只能是包含数字和字母的 10 个 if 语句之一。我没有看到任何语法问题。有人可以帮忙解决错误吗？

谢谢

Answer 1

虽然这不能直接回答您的问题（在 cmets、viz、

461518B1 不是字符串，"461518B1" 或 '461518B1'

（使用引号指定字符串字面量）

我要指出，您可以修改代码以避免冗余，因为您似乎在每个 if/elif` 块中使用相同的代码块：

id_values = ['461518B1', '46154D41', '4615A161', '4616A511', '46193031', '46196771', '461A79D1', '46211881', '465598F1', '9A2DCDE4']

data = arduino.readline() # read data
data = data.strip()       # get rid of whitespace like '\r\n'
print "The data is:",data
if data in id_values:
    try:
        cursor.execute("UPDATE 'ISEF_DB'.'attendance' SET 'present'='1' WHERE 'id' = '" + data + "'")
        dbConn.commit()
        cursor.close()
        print "data inserted"
    except MySQLdb.IntegrityError:
        print "Failed to insert data"
    finally:
        cursor.close()
        print "done"
else:
    print "Card not recognized {}".format(data)