Question

I am using python3.6 and i am getting an error on line 42

num = int(fin.readline()) #reading first value

valueError: invalid literal, for int() with base 10

Any help is appreciated, here is the code. reads from txt file a few integers in an array and sorts them. thank you!

# Function to do insertion sort

def insertionSort(arr):

    # Traverse through 1 to len(arr)

    for i in range(1, len(arr)):

        key = arr[i]

        # Move elements of arr[0..i-1], that are

        # greater than key, to one position ahead

        # of their current position

        j = i-1

        while j >=0 and key < arr[j] :

            arr[j+1] = arr[j]

            j -= 1

        arr[j+1] = key

# Driver code to test above

def main():

    arr = list()    #Creating array list to store the number read from file

   

    fin = open('input.txt', 'r') #Open text file in read mode

    num = int(fin.readline())   # Reading first value as total count of numbers

    #Reading rest of numbers from input file & store it into array

    for i in range(num):

        arr.append(int(fin.readline()))

       

    insertionSort(arr) #Calling function to sort elements of array list

    fout = open('output.txt', 'w') #Open text file in write mode

    for i in range(num):

        fout.write(str(arr[i])+" ")   #Writing data into output file

main()

Answer 1

Note: Since you have not provided the format of your input file. I could only guess the possible problem.

The input text file contains other characters than integers. Such as while converting input to integer, it is encountering some characters such as 'newline character backslash n ' or ' ' which cannot be converted into string. To avoid this problem use rstrip() function as num=int(fin.readline.rstrip()).

Hence, check your input file format. If the problem persists attach input file with question.

The code works correctly with the below input file.

input.txt Notepad File Edit Format View Help 10 10 8 7 6 4 2 1 output.txt - Notepad File Edit Format View Help 1 23 4 5 6 78910