So, I have been looking for a job for quite a while now, and have had some interviews. Thus far, I have not been successful, though.
I just had an interview, where I was asked to solve some things during the interview. Here are some of the questions that I didn’t have an answer to, from the top of my head.
“In Bash, change mode of all jpg-files in the current directory, and sub directories”.
Here, I was first thinking about how to setup the for-loop in bash. There is the do, and done, and somewhere, you need a semicolon.
I also started to think about using find, but was not sure if I needed the flag in xargs to limit the output to one entry per line. While I was contemplating, the interviewer asked how much I had done in Bash, and I said, I mostly did small build scripts. And then he asked about Makefile, so we skipped the first question.
I later checked the solution I was starting to form in my head:
find . -iname *.jpg | xargs chmod 600
That would have worked.
“What does .PHONY in a Makefile mean?”
I have seen it often, but never looked it up.
Now, I have found that it is a directive you put in a Makefile, that is always dirty, thus is always built. This is mostly used for clean and all. A Makefile always has a target, and clean and all are used for cleaning up the build (remove all built binaries and libraries), and to make all projects. If you then have a file in the directory that is called clean or all, it becomes ambiguous for make, if you want to build the file clean or if you want to clean up the build. That’s why you setup a .PHONY directive.
“How do you combine two lists in Javascript or Python”.
This, I should have known. But I guess it is something that I missed by not doing a proper course in Python, or I have simply forgot it. I hate it when I forget the elementary things. I don’t know how often I have to lookup “Hello world” in languages I have used before, because I have forgotten how to start a simple project, or how to output text to command line.
The more detailed question:
“You have:
a=[1,2,3]
b=[4,5,6]
How do you create
c=[1,2,3,4,5,6]?”
I quick-and-dirty-solved it in Python like this:
c=[]
for x in a:
c.append(x)
for x in b:
c.append(x)
This was not an acceptable solution, and we broke off the interview at this point.
When did some searches. I saw, I should have simply tried the +-operator:
c=a+b
In other languages:
In Javascript, you can use concat.
c=a.concat(b);
In C/C++, first C-arrays:
//How do you concatenate c arrays?
int a[3]={1,2,3};
int b[3]={4,5,6};
int c[6];
// You actually don't need to specify the size of the
// array,
// if it is initialized with the {} notation,
// the compiler can infer it:
int d[]={1,2};
//Need to loop through a and b to fill c, and for this,
// need to
// specifically know the sizes of the arrays
const int size1=3;
const int size2=3;
for(int i=0; i < size1; i++)
{
c[i] = a[i];
}
for(int i=0; i < size2; i++)
{
c[i+size1]=b[i];
}
In C++:
// In C++, you should use std::vector
std::vector a_vec;
a_vec.push_back(1);
a_vec.push_back(2);
a_vec.push_back(3);
// In C++ 11, you can use the array initialization as
// well:
std::vector b_vec = { 4, 5, 6};
std::vector c_vec;
c_vec.insert(c_vec.end(), a_vec.begin(), a_vec.end());
c_vec.insert(c_vec.end(), b_vec.begin(), b_vec.end());
It is worrisome, that my memories of some of the basic things are so sketchy, I need to shape up, to call myself senior in any language. Maybe I should stop looking at more different languages (I am currently working my way through SICP - Structure and Interpretation of Computer Programs), and focus on some languages that I would like to work in.
Other resources that deal with what it means to be "Senior Developer": The programmer competence matrix.