Canal-U

1.6. GC and AT contents of DNA sequence

We have designed our first algorithmfor counting nucleotides. Remember, what we have writtenin pseudo code is first declaration of variables. We have several integer variables that are variables which cantake as a value an integer. One, two, three minus five and so on. We have the sequence of characters we want to interpret, declare as a character string oflengths and define. Then we have the initializationof our different variables. This symbol is a symbol for assignment, it means that zero becomes the value of total nb, nbT and soon and so on and here we say: index takes the value one. It means that we position at the beginning of the sequence and what we do is that we repeat allthese blocks of operation for the first position, the second position, the third and so on, so on, until the end of the sequence. And for each position we take the current corrector, here, A for example and we look if itis an A, a C, a G, a T and we increment, we increase by one,the corresponding counter. OK, at the same time we increasethe total number of characters by one and we add one to theindex so that we come from this position to this position.