TypeError: unsupported operand type(s) for -: 'str' and 'int' (Python)

Question

I have written the code for quick sort in python, but this code is throwing an error.

----------


    k=0
    def partition(arr,low_index,high_index):
        key = arr[low_index]
        i = low_index + 1;
        j = high_index

        while True:
            while (i<high_index and key>=arr[i]):
                i+=1
            while (key<arr[j]):
                j-=1
            if i<j:
                arr[i,j] = arr[j,i]
            else:
                arr[low_index,j]=arr[j,low_index]
                return j

    def quicksort(arr,low_index,high_index):
         if low_index < high_index:
            j = partition(low_index,high_index,arr)
            print("Pivot element with index "+str(j)+" has thread "+str(k))
            if left<j:
                k=k+1
                quicksort(arr,low_index, j - 1)
            if i<right:
                k=k+1
                quicksort(arr,j+1,high_index)
         return arr

    n = input("Enter the value n ")
    arr=input("Enter the "+str(n)+" no. of elements ")
    brr=quicksort(arr,0,n-1)
    print("Elements after sorting are "+str(brr))

----------

The error it is throwing is

Enter the value n 4

Enter the 4 no. of elements [5,6,2,7] Traceback (most recent call last): File "C:\Users\devendrabhat\Documents\dev\dev\quick.py", line 38, in brr=quicksort(arr,0,n-1) TypeError: unsupported operand type(s) for -: 'str' and 'int'

Possible duplicate of TypeError: unsupported operand type(s) for /: 'str' and 'int' — Shubham Verma
Python receives input as a string. You need to use the function int() on that input to turn it into an integer and catch possible exceptions. — MKesper

Hironsan Hironsan · Accepted Answer · 2017-02-14T07:16:47

n is string. So you need to change it to int:

n = int(n)

If you input [5,6,2,7] on line 37, python interpret it as string like "[5,6,2,7]". So, you need to convert string to list.

arr = eval(arr)

TypeError: unsupported operand type(s) for -: 'str' and 'int' (Python)

3 Answers