Why glGenVertexArray()gives access violation error?

[hsunteik]

My old error,the NullFunctionError is solved by creating a opengl context before calling the opengl function,but now I get a new error,that is the access violation writing to location error and is caused by the same function ,the glGenVertexArray function.

1)what is happening?

2)how do I fix it?

3) is the difference between 'vao=glGenVertexArray(1)' and glGenVertexArray(1,vbo)

my code here