Write me a hello world program in c
Sure! Here's a simple Hello, world! program in C:

#include <stdio.h>

int main() {
  printf(Hello, world!\n);
  return 0;
}

This program uses the printf function from the stdio.h library to print the message Hello, world! to the console. The \n character at the end of the string adds a newline to the output, so the prompt will start on a new line after the message is displayed. Finally, the return 0; statement at the end of the main function is used to indicate that the program has completed successfully.
Thank you, please convert it to work in python and javascript
Sure! For python, you could simply do `print(Hello, world!)` in a file and it would work fine, but to be more analogous to the C example, you can define a main function too:

```python
def main():
    print(Hello, world!)

if __name__ == __main__:
    main()
```

In this code, there is a function called `main()` that prints the phrase Hello, world! when the Python interpreter executes it. There is also a conditional (or if) statement that checks the value of `__name__` and compares it to the string `__main__`. When the if statement evaluates to `True`, the Python interpreter executes `main()`. 

For Javascript, similar to python, you could simply do it with one line, `console.log('Hello, world!');`, which will log the output to the console. Other alternatives can write it into a webpage or pop up an alert. While you could define a `main` function in a file and execute it explicitly, to do so would be superfluous, as javascript does not have a concept of a `main` function.