std

Noob here, I'm trying to compile this segment of code from Bjarne Stroustrup's 'The C++ Programming Language' but CodeBlocks keeps throwing me this error. The code is about range checking an array held in a vector function. Here is the code: #include <iostream> #include <vector> #include <array> using namespace std; int i = 1000; template<class T> class Vec : public vector<T> { public: Vec() : vector<T>() { } T& operator[] (int i) {return at(i); } const T& operator[] (int i) const {return at(i); } //The at() operation is a vector subscript operation //that throws an exception of type out_of

This question already has an answer here: Iterator invalidation rules 5 answers when and how are iterators invalidated in a map when using the erase method ? for example : std :: map < int , int > aMap ; aMap [ 33 ] = 1 ; aMap [ 42 ] = 10000 ; aMap [ 69 ] = 100 ; aMap [ 666 ] = -1 ; std :: map < int , int > :: iterator itEnd = aMap.lower_bound ( 50 ) ; for ( std :: map < int , int > :: iterator it = aMap.begin ( ) ; it != itEnd ; // no-op ) { aMap.erase ( it ++ ) ; } the erased iterator will surely become invalid (it's incremented while still valid) but what about the others? if I'm not wrong

Greetings. I don't know very well how to explain myself, but I believe a piece of code will make you understand what I'm intenting to do : template<class A, class B> void myFunction(A<B>& list) { typename A<B>::iterator current = list.begin(); typename A<B>::iterator end = list.end(); while (current != end) { current++; } } Where A is an STL container (vector, list...). It's like inception, but with templates : a template, inside a template, etc... The thing is : what do you do when one of the params of your template is itself a template... and still want to support every types supported by

I have a string vector like {"1.2","3.4","0.5","200.7"} . I would like to convert each element into double and store it in a vector<double> . Like so {1.2,3.4,0.5,200.7} What would be the best way to do this? I know of the std::stod(string, size) ; But I am hoping for a better way to do this. I was looking for something like: vector<double> doubleVector = convertStringVectortoDoubleVector(myStringVector); There doesn't seem to be anything like that; so what is the next best thing? EDIT: Here's what I ended up using: std::vector<double> convertStringVectortoDoubleVector(const std::vector<std:

I am trying to get the vector source code to see how the standard std or stl vector is implemented. This is for learning purpose. Now the question is where can i find the source code. Even source code of other C++ Container also helpful. Steve Townsend There is no 'standard' vector - the standard defines behaviour and interface (and some implementation details, such as contiguous storage) but the code is a matter for compiler writers to determine. Your compiler should have its own <vector> header file, have you checked for this on your build include path? Once you find that you should also see

The negative implication of this is noted in the man page: NOTES Trying to take the absolute value of the most negative integer is not defined. What's the reasoning behind this and what's the best recourse for a person who would like to avoid undefined behavior? Do I have to resort to something like: unsigned uabs(signed val) { return val > 0 ? val : (val == 1U << ((sizeof(val) * 8) - 1)) ? -1U : -val; } (Intentionally hacky to emphasize displeasure with stdlib ;-) Example Say you had a 4-bit signed value (for ease of understanding). unsigned max is 15, signed (positive) max is 7, signed

I get error when I try to do this: path p = "somepath"; FILE* file = fopen(p.c_str(), "r"); I get: argument of type "const boost::filesystem::path::value_type *" is incompatible with parameter of type "const char *" Could anyone tell me what I'm doing wrong? Thanks If you're under Windows, that value_type is wchar_t , and will fail in the conversion for fopen (that needs a char* ). As per the documentation, it seems you have to use the string() method to obtain a standard string with a default code conversor ( wchar_t -> char ): FILE* file = fopen(p.string().c_str(), "r"); 来源： https:/

I weren't able to find that question, and it's an actual problem I'm facing. I have a file loading utility that returns std::vector<unsigned char> containing whole file contents. However, the processing function requires contiguos array of char (and that cannot be changed - it's a library function). Since the class that's using the processing function stores a copy of the data anyway, I want to store it as vector<char> . Here's the code that might be a bit more illustrative. std::vector<unsigned char> LoadFile (std::string const& path); class Processor { std::vector<char> cache; void

I think this is a very basic question but I couldn't just figure it out. I was used to using arrays in C++ but I'm now starting to learn vectors. I was making a test code, and I came across a question. First of all, here's the code I made: #include <iostream> #include <vector> #include <numeric> using namespace std; int main(){ vector<double> score(10); for(vector<double>::size_type i=0;i<20;i++) { cout<<"Enter marks for student #"<<i+1<<":"<<flush; cin>>score[i]; } double total = accumulate(score.begin(), score.end(),0); cout<<"Total score:"<<total<<endl<<"Average score:"<<total/score.size()<

I am trying to spawn a thread from within my class and the thread executes a particular method in my class. The code looks like this: class ThreadClass{ int myThread(int arg){ // do something } void createThread(){ thread t = thread(myThread,10); } } ; This code on compilation throws an error saying std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = int (ThreadClass::*)(int), _Args = {int}] no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘int (ThreadClass::*&&)(int)’ I am not sure what is the actual bug here. Can someone help me with this? Thanks