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[英]How to print elements of a std::vector<std::any> vector in C++?
[英]Why is the std::vector not giving any outputs in c++
我不明白为什么,但在我将 class 指针放入数组后,std::vector 没有提供任何信息。
// runs at start
void States::AssignState(GameState* state) {
_nextVacentState++;
_states.push_back(state);
}
// executes in a loop
void States::ExecuteCurrentState() {
// protection incase there is nothing in the array or the current state is not grater than the size of the array (not the problem after i nerrowed the problem down)
if (_nextVacentState == 0) std::cout << "Error: There is no states, setup some states then try again" << std::endl; return; // there is no states
if (_currentState >= _states.size() - 1) std::cout << "Error: Current State is grater than all possable states" << std::endl; return;
// The program just freezes at this and i can figure out why
_states[0]->tick();
std::printf("S");
}
这是我建议养成对所有if
语句使用花括号的习惯的原因之一,即使是那些位于一行中的语句。
问题线路:
if (_nextVacentState == 0) std::cout << "Error: There is no states, setup some states then try again" << std::endl; return;
让我们添加一些换行符以更清楚地了解正在发生的事情
if (_nextVacentState == 0)
std::cout << "Error: There is no states, setup some states then try again" << std::endl;
return;
该return
语句将无条件执行,因为只有if(_nextVacentState==0)
之后的第一条语句实际上是if
的一部分。 所以编译器执行它就好像它是这样写的:
if (_nextVacentState == 0)
{
std::cout << "Error: There is no states, setup some states then try again" << std::endl;
}
return;
但是,你想要的需要这样写:
if (_nextVacentState == 0)
{
std::cout << "Error: There is no states, setup some states then try again" << std::endl;
return;
}
if
还要检查_currentState
,您在下一个问题中也会遇到同样的问题。
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