我目前正在编写一个从txt文件中读取记录的程序，并在屏幕上打印数据：
GRADE REPORT
NAME COURSE GRADE
-----------------------------------------------------------
JOE FRITZ AMERICAN GOVERNMENT B
CALCULUS I A
COMPUTER PROGRAMMING B
ENGLISH COMPOSITION A
Total courses taken = 4
LANE SMITH FUND. OF DATA PROCESSING B
INTERMEDIATE SWIMMING A
INTRO. TO BUSINESS C
Total courses taken = 3
JOHN SPITZ CHOIR C
COLLEGE STATISTICS B
ENGLISH LITERATURE D
INTRO. TO BUSINESS B
Total courses taken = 4
Total courses taken by all students = 11
Run complete. Press the Enter key to exit.
这是从中读取的文本文件：
JOE FRITZ AMERICAN GOVERNMENT B
JOE FRITZ CALCULUS I A
JOE FRITZ COMPUTER PROGRAMMING B
JOE FRITZ ENGLISH COMPOSITION A
LANE SMITH FUND. OF DATA PROCESSING B
LANE SMITH INTERMEDIATE SWIMMING A
LANE SMITH INTRO. TO BUSINESS C
JOHN SPITZ CHOIR C
JOHN SPITZ COLLEGE STATISTICS B
JOHN SPITZ ENGLISH LITERATURE D
JOHN SPITZ INTRO. TO BUSINESS B
这是我的代码：
# VARIABLE DEFINITIONS
name = ""
course = ""
grade = ""
recordCount = 0
eof = False
gradeFile = ""
#-----------------------------------------------------------------------
# CONSTANT DEFINITIONS
#-----------------------------------------------------------------------
# FUNCTION DEFINITIONS
def startUp():
global gradeFile
gradeFile = open("grades.txt","r")
print ("grade report\n").center(60).upper()
print "name".upper(),"course".rjust(22).upper(),"grade".rjust(32).upper()
print "-" * 60
readRecord()
def readRecord():
global name, course, grade
studentRecord = gradeFile.readline()
if studentRecord == "":
eof = True
else:
name = studentRecord[0:20]
course = studentRecord[20:50]
grade = studentRecord[50:51]
eof = False
def processRecords():
numOfRecs = 0
while not eof:
numOfRecs += 1
printLine()
readRecord()
return numOfRecs
def printLine():
print name, course.rjust(3), grade.rjust(3)
def closeUp():
gradeFile.close()
print "\nTotal courses taken by all students = ",recordCount
#-----------------------------------------------------------------------
# PROGRAM'S MAIN LOGIC
startUp()
recordCount = processRecords()
closeUp()
raw_input("\nRun complete. Press the Enter key to exit.")
结果只是打印txt文件的最后一行并且卡在一个循环中。任何帮助将不胜感激。谢谢你的时间。
答案 0 :(得分：5)
为什么不在一个功能中完成所有操作 -
def processRecords():
print ("grade report\n").center(60).upper()
print "name".upper(),"course".rjust(22).upper(),"grade".rjust(32).upper()
print "-" * 60
rec_count = 0
for line in open("grades.txt","r"):
name = line[0:20]
course = line[20:50]
grade = line[50:51]
print name, course.rjust(3), grade.rjust(3)
rec_count += 1
return rec_count
在这一个单一功能中压缩所有这些功能。你似乎编程很像C代码。这是Python！
除非必须，否则尽量避免使用globals。只是我遵循的原则。显然，在这种情况下你不需要。
答案 1 :(得分：4)
您必须在eof中将global声明为readRecord()：
def readRecord():
global eof, name, course, grade
否则，当eof为空时，您对studentRecord所做的更改将无法在readRecord()范围之外生效。
答案 2 :(得分：3)
在此设计中，需要将“eof”添加到readRecord（）
中的全局列表中否则分配它会创建一个新的局部变量，进程Records（）永远不会看到。
答案 3 :(得分：3)
您需要在readRecord（）中添加eof到全局变量：
...
def readRecord():
global name, course, grade, eof
...
但是你的解决方案有点不像pythonic。更简短，更灵活的事情：
import re
print ("grade report\n").center(60).upper()
print "name".upper(),"course".rjust(22).upper(),"grade".rjust(32).upper()
print "-" * 60
for line in open("grades.txt"):
name, course, grade = re.split(" *", line.strip())
print "%-21s%-34s%-21s" % (name, course, grade)
raw_input("\nRun complete. Press the Enter key to exit.")
正则表达式是一个非常简单的表达式，可以分割多个空格。如果您的分隔符是其他内容，则将正则表达式" *"替换为分隔符。
这是一个使用python dicts跟踪学生的课程和成绩的版本（即你的目标输出）：
import re
print ("grade report\n").center(60).upper()
print "name".upper(),"course".rjust(22).upper(),"grade".rjust(32).upper()
print "-" * 60
grades = {}
total_courses = 0
for line in open("grades.txt"):
name, course, grade = re.split(" *", line.strip())
if not grades.get(name): grades[name] = []
grades[name].append([course, grade])
for name, data in grades.items():
for course, grade in data:
print "%-21s%-34s%s" % (name, course, grade)
name = ""
print "%-21sTotal courses taken = %d\n" % (" ", len(data))
total_courses += len(data)
print "Total courses taken by all students = %d" % total_courses
raw_input("\nRun complete. Press the Enter key to exit.")
答案 4 :(得分：2)
你在这里错过global，而你的while循环检查全局变量eof，你的readRecord函数确实设置了local变量{{1 }}
答案 5 :(得分：2)
您必须在eof中的全局变量列表中添加readRecord。
但是，您说任何帮助，所以这是另一个版本：
import itertools as it, operator as op
import collections
Record= collections.namedtuple("Record", "name course grade")
grouper= op.itemgetter(0) # or op.attrgetter('name')
def file_reader(fobj_in):
for line in fobj_in:
name= line[:20].rstrip()
course= line[20:50].rstrip()
grade= line[50:].rstrip()
yield Record(name, course, grade)
def process(fn_in, fobj_out):
for name, records in it.groupby(file_reader(fobj_in), grouper):
out_name= name
for index, record in enumerate(records, 1):
fobj_out.write(
"%-20.19s%-36.35s%s\n" % (out_name, record.course, record.grade)
)
out_name= ''
fobj_out.write("%20sTotal courses taken = %d\n" % ('', index))
if __name__ == "__main__":
import sys
with open('so4009899.txt', 'r') as fobj_in:
process(fobj_in, sys.stdout)
答案 6 :(得分：1)
如果 为了'结构'而使用许多函数，请考虑将参数传递给函数而不是使用全局变量。这是一个小小的变化，说明了我的意思。
def startUp():
print ("grade report\n").center(60).upper()
print "name".upper(),"course".rjust(22).upper(),"grade".rjust(32).upper()
print "-" * 60
processRecords()
def processRecords():
numOfRecs = 0
for line in open("grades.txt","r"):
numOfRecs += 1
printLine(line)
return numOfRecs
def printLine(studentRecord):
name = studentRecord[0:20]
course = studentRecord[20:50]
grade = studentRecord[50:51]
print name, course.rjust(3), grade.rjust(3)
def closeUp(recordCount):
print "\nTotal courses taken by all students = ",recordCount
startUp()