File10. Дан файл целых чисел. Создать новый файл, содержащий те же элементы, что и исходный файл, но в обратном порядке.

Решение на Python 3:

import random

def CountF(fname):
    N = 0
    try:
        with open(fname,'r') as f:
            for line in f:
                N += 1
                #print(N,":",line)
    except IOError:
        return -1
    finally:
        return N

def GetLineN(fname,N):
    line = ""
    k = 0
    try:
        with open(fname,'r') as f:
            for line in f:
                k += 1
                if k == N:
                    break
    except IOError:
        print('Open error: ',file1)
    return line.strip()


file1 = "file10_1.txt"
file2 = "file10_2.txt"
print("Input file: ",file1)
print("Output file: ",file2)
print()

N = CountF(file1)
print("Number of records:",N)
while N > 0:
    last_line = GetLineN(file1,N)
    try:
        f = open(file2, "a")
        try:
            f.write(last_line+"\n")
        finally:
            f.close()
    except IOError:
        print('Write error: ',file2)
    N -= 1

Вариант 2

import random

def CountF(fname):
    N = 0
    try:
        with open(fname,'r') as f:
            for line in f:
                N += 1
                #print(N,":",line)
    except IOError:
        return -1
    finally:
        return N

def GetLineN(fname,N):
    line = ""
    k = 0
    try:
        with open(fname,'r') as f:
            for line in f:
                k += 1
                if k == N:
                    break
    except IOError:
        print('Open error: ',file1)
    return line.strip()


file1 = "file10_1.txt"
file2 = "file10_2.txt"
print("Input file: ",file1)
print("Output file: ",file2)
print()

N = CountF(file1)
print("Number of records:",N)
last_line = GetLineN(file1,N)
try:
    f = open(file2, "w")
    try:
        f.write(last_line+"\n")
    finally:
        f.close()
except IOError:
    print('Write error: ',file2)

N -= 1
while N > 0:
    last_line = GetLineN(file1,N)
    try:
        f = open(file2, "a")
        try:
            f.write(last_line+"\n")
        finally:
            f.close()
    except IOError:
        print('Write error: ',file2)
    N -= 1