Hungarian notation in a random bitcoin file I opened: coins.cpp

if (!fZero) {
nLastUsedByte = b + 1;
nNonzeroBytes++;
}

See the letters preceding each variable? Those tell you what type of variable they are. Here I suspect "f" is for float and "n" is for "integer". This is not a common style for programming, and especially this kind of it ("systems hungarian") is associated with Microsoft.