How do I get a substring of a string in Python?
Python calls this concept “slicing” and it works on more than just strings. Take a look here for a comprehensive introduction.
Why is it not possible to fake an IP address?
It is fully possible to send data with a fake sender IP. You’ll have a hard time getting replies though, since the replies will be sent to the fake IP and never reach you. Additionally, if you send data with a “from” IP that a router doesn’t expect to arrive from you, the router will … Read more
How to prevent the “Confirm Form Resubmission” dialog?
How do I clean information in a form after submit so that it does not show this error after a page refresh? See image (from chrome): The dialog has the text: The page that you’re looking for usedinformation that you entered. Returning to thatpage might cause any action you took to berepeated. Do you want … Read more
Why there is no do while loop in python
There is no do…while loop because there is no nice way to define one that fits in the statement: indented block pattern used by every other Python compound statement. As such proposals to add such syntax have never reached agreement. Nor is there really any need to have such a construct, not when you can just do: and have the exact … Read more
How to format strings in Java
In addition to String.format, also take a look java.text.MessageFormat. The format less terse and a bit closer to the C# example you’ve provided and you can use it for parsing as well. For example: A nicer example takes advantage of the varargs and autoboxing improvements in Java 1.5 and turns the above into a one-liner: MessageFormat is … Read more
TypeError: list indices must be integers or slices, not str
First, array_length should be an integer and not a string: Second, your for loop should be constructed using range: Third, i will increment automatically, so delete the following line: Note, one could also just zip the two lists given that they have the same length:
Using or ‘|’ in regex [duplicate]
It’s because you are trying to match against the entire string instead of the part to find. For example, this code will find that only a part of the string is conforming to the present regex: When you want to match an entire string and check if that string contains he|be|de use this regex .*(he|be|de).* . means … Read more
Istio Ingress resulting in “no healthy upstream”
Although this is a somewhat general error resulting from a routing issue within an improper Istio setup, I will provide a general solution/piece of advice to anyone coming across the same issue. In my case the issue was due to incorrect route rule configuration, the Kubernetes native services were functioning however the Istio routing rules … Read more
Using “with open() as file” method, how to write more than once? [duplicate]
The w flag means “open for writing and truncate the file”; you’d probably want to open the file with the a flag which means “open the file for appending”. Also, it seems that you’re using Python 2. You shouldn’t be using the b flag, except in case when you’re writing binary as opposed to plain text content. In Python 3 your … Read more
How to use execvp() to execute a command
The prototype of execvp is It expects a pointer to char as the first argument, and a NULL-terminated pointer to an array of char*. You are passing completely wrong arguments. You are passing a single char as first argument and a char* as the second. Use execlp instead: So Also the convention in UNIX is to print error messages to stderr and a process with an error should have … Read more