How do you convert a string to an integer in Python?

In Python, converting a string to an integer is accomplished using the int() function. When you pass a string that represents an integer, such as "123", to this function, it processes the string and returns the corresponding integer value, which in this case would be 123. This function can also handle various formats, including strings with leading whitespace or those prefixed with a sign indicator such as "+" or "-". However, it's important to note that the string must be entirely numeric or conform to valid integer formatting; otherwise, the function will raise a ValueError.

The other choices presented do not perform the task of converting a string to an integer. The str() function is used to create a string representation of an object and will not convert a string into an integer. The float() function converts a string to a floating-point number, not an integer, which can lead to a loss of precision if the original string represents a whole number. Lastly, toInteger() is not a valid built-in function in Python, making it an incorrect choice for string conversion.