Question

I have a file with data listed as follows:

0,       2,    10 10,       8,    10 10,       10,   10 10,       16,   10 15,       10,   16 17,       10,   16 

I want to be able to input the file and split it into three arrays, in the process trimming all excess spaces and converting each element to integers.

For some reason I can’t find an easy way to do this in c++. The only success I’ve had is by inputting each line into an array, and then regexing out all the spaces and then splitting it up. This entire process took me a good 20-30 lines of code and its a pain to modify for say another separator(eg. space), etc.

This is the python equivalent of what I would like to have in C++:

f = open('input_hard.dat') lines =  f.readlines() f.close()  #declarations inint, inbase, outbase = [], [], []  #input parsing for line in lines:     bits = string.split(line, ',')     inint.append(int(bits[0].strip()))     inbase.append(int(bits[1].strip()))     outbase.append(int(bits[2].strip())) 

The ease of use of doing this in python is one of the reasons why I moved to it in the first place. However, I require to do this in C++ now and I would hate to have to use my ugly 20-30 line code.

Any help would be appreciated, thanks!

Answer 1

There is really nothing wrong with fscanf, which is probably the fastest solution in this case. And it’s as short and readable as the python code:

FILE *fp = fopen('file.dat', 'r'); int x, y, z; std::vector<int> vx, vy, vz;  while (fscanf(fp, '%d, %d, %d', &x, &y, &z) == 3) {   vx.push_back(x);   vy.push_back(y);   vz.push_back(z); } fclose(fp);