[HELP] update data in the .txt file

Question

i have the following .txt file contain

1 2
2 3

i want to update the value of 2 to 0 so the output would be like this,

1 0
2 3

i have no clue how this can be done using fstream header. I know how to write data to file and display data from file. But how to update that specific value in a specific line?