how to define dtype of each column before actually reading csv file

import pandas as pd 

# ...[.].csv = your .csv file 
# datatype = dtype you want to define.
read = pd.read_csv('......[.]csv',dtype={'name_column':'datatype'})

Here is what the above code is Doing:
1. We’re using the read_csv function from pandas.
2. We’re defining the file we want to read.
3. We’re defining the datatype for the column we want to change.
4. We’re storing the dataframe in a variable called read.