很抱歉,这是一个愚蠢的问题,但是我没有太多的Python经验
我具有比较文件的功能
def compare_files(file1, file2):
fname1 = file1
fname2 = file2
# Open file for reading in text mode (default mode)
f1 = open(fname1)
f2 = open(fname2)
# Print confirmation
#print("-----------------------------------")
#print("Comparing files ", " > " + fname1, " < " +fname2, sep='\n')
#print("-----------------------------------")
# Read the first line from the files
f1_line = f1.readline()
f2_line = f2.readline()
# Initialize counter for line number
line_no = 1
# Loop if either file1 or file2 has not reached EOF
while f1_line != '' or f2_line != '':
# Strip the leading whitespaces
f1_line = f1_line.rstrip()
f2_line = f2_line.rstrip()
# Compare the lines from both file
if f1_line != f2_line:
########## If a line does not exist on file2 then mark the output with + sign
if f2_line == '' and f1_line != '':
print ("Line added:Line-%d" % line_no + "-"+ f1_line)
#otherwise output the line on file1 and mark it with > sign
elif f1_line != '':
print ("Line changed:Line-%d" % line_no + "-"+ f1_line)
########### If a line does not exist on file1 then mark the output with + sign
if f1_line == '' and f2_line != '':
print ("Line removed:Line-%d" % line_no + "-"+ f1_line)
# otherwise output the line on file2 and mark it with < sign
#elif f2_line != '':
#print("<", "Line-%d" % line_no, f2_line)
# Print a blank line
#print()
#Read the next line from the file
f1_line = f1.readline()
f2_line = f2.readline()
#Increment line counter
line_no += 1
# Close the files
f1.close()
f2.close()
我想将功能输出打印到文本文件
result=compare_files("1.txt", "2.txt")
print (result)
Line changed:Line-1-aaaaa
Line added:Line-2-sss
None
我尝试了以下操作:
f = open('changes.txt', 'w')
f.write(str(result))
f.close
但在None.txt中仅打印无
我正在使用“解决方法” sys.stdout,但想知道是否还有其他方法可以代替重定向打印输出。
如果在函数输出中我指定return而不是print,那么我仅将第一条输出行(换行:Line-1-aaaaa)添加到changes.txt
答案 0 :(得分:1)
您的'compare_files'函数不返回任何内容,因此没有任何内容写入该文件。使函数“ 返回”生效,它应该可以工作。
答案 1 :(得分:0)
您的功能未返回任何内容,因此您正在打印“无”。如果您希望所有打印都转到文件而不是默认情况下像stdout一样,则可以像对待返回值一样处理每个打印语句。
或者您可以像在here中一样对整个程序使用重定向。
答案 2 :(得分:0)
由于默认情况下您未返回任何内容,因此该函数返回None
,从而反映在您的changes.txt
文件中。您可以创建一个变量,该变量存储所需的输出并返回。
def compare_files(file1, file2):
fname1 = file1
fname2 = file2
# Open file for reading in text mode (default mode)
f1 = open(fname1)
f2 = open(fname2)
output_string = ""
# Print confirmation
# print("-----------------------------------")
# print("Comparing files ", " > " + fname1, " < " +fname2, sep='\n')
# print("-----------------------------------")
# Read the first line from the files
f1_line = f1.readline()
f2_line = f2.readline()
# Initialize counter for line number
line_no = 1
# Loop if either file1 or file2 has not reached EOF
while f1_line != '' or f2_line != '':
# Strip the leading whitespaces
f1_line = f1_line.rstrip()
f2_line = f2_line.rstrip()
# Compare the lines from both file
if f1_line != f2_line:
########## If a line does not exist on file2 then mark the output with + sign
if f2_line == '' and f1_line != '':
print("Line added:Line-%d" % line_no + "-" + f1_line)
output_string += "Line added:Line-%d" % line_no + "-" + f1_line + "\n"
# otherwise output the line on file1 and mark it with > sign
elif f1_line != '':
print("Line changed:Line-%d" % line_no + "-" + f1_line)
output_string += "Line changed:Line-%d" % line_no + "-" + f1_line +"\n"
########### If a line does not exist on file1 then mark the output with + sign
if f1_line == '' and f2_line != '':
print("Line removed:Line-%d" % line_no + "-" + f1_line)
output_string += "Line removed:Line-%d" % line_no + "-" + f1_line +"\n"
# otherwise output the line on file2 and mark it with < sign
# elif f2_line != '':
# print("<", "Line-%d" % line_no, f2_line)
# Print a blank line
# print()
# Read the next line from the file
f1_line = f1.readline()
f2_line = f2.readline()
# Increment line counter
line_no += 1
# Close the files
f1.close()
f2.close()
return output_string
答案 3 :(得分:0)
您的compare_files()
仅打印,但不将任何内容传递给其调用方。
如果要将一项传递给呼叫者,请使用return
。函数流程到此结束。
如果要将多个项目传递给呼叫者,请yield
。使用yield
会将函数转换为生成器函数。调用生成器函数会生成一个生成器对象,可以对其进行迭代。
示例:
def produce_strings():
for i in ['a', 'b', 'c']:
yield i + "x"
result = "\n".join(produce_strings())
print(result) # prints a line end separated string made of "ax", "bx" and "cx".