Write a function that returns `true` if the `string` passed in parameter only contains alphanumerical characters or is empty, and that returns `false` otherwise.
Write a function that returns `true` if the `string` passed in parameter only contains alphanumerical characters or is empty, and returns `false` otherwise.
Write a function that returns the concatenation of all the `string` of a slice of `string`**separated** by the separator passed in argument.
Write a function that simulates the behaviour of the `Join` function in Go. This function returns the concatenation of all the strings of a slice of strings **separated** by a separator passed in argument.
- Write a function that transforms a number within a `string` in a number represented as an `int`.
- Write a function that transforms a number within a `string`, in a number represented as an `int`.
- For this exercise the handling of the signs + or -**has** to be taken into account. If one of the signs is encountered before any number it should determine the sign of the returned `int`.
- For this exercise the handling of the sign`-`**has** to be taken into account. If the sign is encountered before any number it should determine the sign of the returned `int`.
- This function will **only**have to return the`int`. In case of invalid input, the function should return `0`.
- This function will **only**return an`int`. In case of invalid input, the function should return `0`.
- Note: There will never be more than one sign by string in the tests.
- **Note**: There will never be more than one sign by `string` in the tests.