Recent questions tagged C++

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c++ - Dijkstra Shortest Path with VertexList = ListS in boost graph

I am quite new to Boost graph. I am trying to adapt an example for finding Dijkstra Shortest Path algorithm which ... what I am doing wrong.. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Overload operators as member function or non-member (friend) function?

I am currently creating a utility class that will have overloaded operators in it. What are the pros and cons of ... a best practice for this? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - `auto` specifier type deduction for references

Let's consider the following code snippet void Test() { int x = 0; int& rx = x; int* px = &x; ... GetBigClass(); // unexpected copy is performed See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to Handle SIGABRT signal?

Here is the code on which I set my handler for SIGABRT signal then I call abort() but handler does not get ... ; return 0; } PROGRAM OUTPUT: See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Using SFINAE to check for global operator<<?

I want to have several overloaded, global to_string() functions that take some type T and convert it to its string ... e.g., Boost. Thanks! See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Sorting std::strings with numbers in them?

I'm currently sorting by the std::string < operator. The problem with it is that: 30 < 9. The 30 shows up ... I'm using utf 8 encoding. Thanks See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - how to show enter password in the form of Asterisks(*) on terminal

I want to write a simple C program to verify the password, for example if password is equal to 1234 then i want to ... c or c++. Platform : UNIX See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Distinguish between single and double click events in Qt

I have a QAbstractItemView that needs to react to single and double click events. The actions are different depending on ... I am using Qt 4.6 See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Stopping the debugger when a NaN floating point number is produced

I have an C++ program. Somewhere in the program (hard to reproduce, but reproduceable) a caclculation results in ... under ubuntu linux 10.10. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to use C++11 enum class for flags

Say I have such a class: enum class Flags : char { FLAG_1 = 1; FLAG_2 = 2; FLAG_3 = 4; FLAG_4 = 8; }; ... enum I have not defined value for 7. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Can I delete[] a pointer that points into an allocated array, but not to the start of it?

I'm wondering specifically about the following situation (which I discovered in some code I have to work with) ... certainly doesn't feel right. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why callback functions needs to be static when declared in class

I was trying to declare a callback function in class and then somewhere i read the function needs to be ... .my_func(Obj.callback_func); } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Explicit copy constructor

I have extended std::string to fulfil my needs of having to write custom function build into string class called ... of "guessing proper cast". See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Is there a use for function declarations inside functions?

We can declare functions inside functions (I wanted a local variable, but it parses as a function declaration): ... an obscure use for this? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Can raw pointers be used instead of iterators with STL algorithms for containers with linear storage?

I have a custom vector container that internally stores item a linear array. Last night, I was trying to ... I'm breaking data encapsulation. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why do objects returned from bind ignore extra arguments?

Suppose I have a function that takes two arguments, void f(int x, int y); and I want to bind one of ... that would be rejected anyplace else. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - //! [0] in Qt source code

What is the meaning of the //! [n] (n = 0, 1, 2 ...) markup in the C++/QML sources in the Qt sample ... elapsed); painter.end(); } //! [2] See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why put the constant before the variable in a comparison?

I noticed for a while now the following syntax in some of our code: if( NULL == var){ //... } ... style, or does it somehow affect performance? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Assign a nullptr to a std::string is safe?

I was working on a little project and came to a situation where the following happened: std::string myString; ... ? or it will segfault? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - dynamic_cast from "void *"

According to this, void* has no RTTI information, therefore casting from void* is not legal and it make sense ... you please clarify the issue. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How performing multiple matrix multiplications in CUDA?

I have an array of square matrices int *M[10]; so that M[i] locates the first element of the i-th matrix. I want ... ); cudaFree(devP[ i ]); } } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - comparison between string literal

This very simple code: #include <iostream> using namespace std; void exec(char* option) { cout << "option is " ... is to use std::string? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - (Qt 5.4.1) This application failed to start because it could not find or load the Qt platform plugin "xcb"

I reinstalled my ubuntu 14.04 and Qt 5.4.1 and Qtcreator. Qt 5.4.1 was built from source with "- ... the error when I execute this file. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Using bts assembly instruction with gcc compiler

I want to use the bts and bt x86 assembly instructions to speed up bit operations in my C++ code on the ... replace TestBit by a bt instruction? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Resetting the State of a Stream

I have a question which is slightly similar to this question on stackoverflow std::cin.clear() fails to restore input ... ; } } return 0; } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - ostream chaining, output order

I have a function that takes an ostream reference as an argument, writes some data to the stream, and then ... also chain with operator<<? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Qt3d. Draw transparent QSphereMesh over triangles

I have a function that draws triangles through OpenGL I draw two triangles by pressing a button (function ... QEntity(view3dRootEntity_); } } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - C++11 "overloaded lambda" with variadic template and variable capture

I'm investigating a C++11 idiom which might be called "overloaded lambda": http://cpptruths.blogspot.com/2014/05/fun-with ... ); f(argv[0]); } See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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