Implement the function
atoi. Input the string as an argument and convert it into an integer and return it. If the string is a valid input, the function should return the equivalent integer number for the given string number. If no valid conversion occurs, the function should return 0.
Write a function
atoi that should have the following parameter(s):
1.) a = string
The function should return,
Output is -1 as input is not integer only.
• The length of the string will be greater than or equal to 1 and less than or equal to 100.