Your code has undefined behaviour because you are trying to assign l from an uninitialised array str. I’m guessing you got your functions confused and meant to write the opposite That code assigns l to str. Use the following code to work out how big str needs to be
OK some answers about malloc were already posted. The more interesting part is how free works (and in this direction, malloc too can be understood better). In many malloc/free implementations, free does normally not return the memory to the operating system (or at least only in rare cases). The reason is that you will get gaps in … Read more
According to the C++ Standard 1 The && operator groups left-to-right. The operands are both contextually converted to bool (Clause 4). The result is true if both operands are true and false otherwise. Unlike &, && guarantees left-to-right evaluation: the second operand is not evaluated if the first operand is false. and 1 The || operator groups left-to-right. … Read more
Note – You may also want to check other answers, especially the one with decltype and lambda You should declare a class Compare and overload operator() for it like this: Or, if you for some reasons can’t make it as class, you could use std::function for it:
In C++11, use std::stoi as: std::string s = “10”; int i = std::stoi(s); Note that std::stoi will throw exception of type std::invalid_argument if the conversion cannot be performed, or std::out_of_range if the conversion results in overflow(i.e when the string value is too big for int type). You can use std::stol or std:stoll though in case int seems too small for the input string. In C++03/98, any of the following can be … Read more
To understand this you’ll first need to understand pointers and references. I’ll simply explain the type declaration syntax you’re asking about assuming you already know what pointers and references are. In C, it is said that ‘declaration follows use.’ That means the syntax for declaring a variable mimics using the variable: generally in a declaration … Read more
std::string doesn’t contain such function but you could use stand-alone replace function from algorithm header.
Here is the complete source code, updated from your source:
I’ve never heard of a best practice for this specific question. However, one best practice in general is to use the simplest solution that solves the problem. In this case the array-style access (or c-style if you want to call it that) is the simplest way to iterate while having the index value available. So … Read more
Actually there are quite a few methods. C++03 Classic for loop: for(std::vector<int>::iterator it = vector.begin(); it != vector.end(); ++it) sum_of_elems += *it; Using a standard algorithm: #include <numeric> sum_of_elems = std::accumulate(vector.begin(), vector.end(), 0); Important Note: The last argument’s type is used not just for the initial value, but for the type of the result as well. If you … Read more