Could I have help diagnosing the problem in this?

draw_triangle

#define GLEW_STATIC
#include <GL/glew.h>

#include "SDL2/SDL.h"
#include "SDL2/SDL_opengl.h"

#include "iostream"

const GLchar* vertexSource =
    "#version 150 core\n"
    "in vec2 position;"
    "void main() {"
    "   gl_Position = vec4(position, 0.0, 1.0);"
    "}";

const GLchar* fragmentSource =
    "#version 150 core\n"
    "out vec4 outColor;"
    "void main() {"
    "   outColor = vec4(1.0, 1.0, 1.0, 1.0);"
    "}";

int main() {
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, 
                        SDL_GL_CONTEXT_PROFILE_CORE);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);

    SDL_Init(SDL_INIT_VIDEO);
    SDL_Window* window = SDL_CreateWindow("triangle", 50, 50, 800, 600, SDL_WINDOW_OPENGL);
    SDL_GLContext context = SDL_GL_CreateContext(window);

    glewExperimental = GL_TRUE;
    glewInit();

    GLuint vao;
    glGenVertexArrays(1, &vao);
    glBindVertexArray(vao);
    
    GLuint vbo;
    glGenBuffers(1, &vbo);

    GLfloat vertices[] = {0.0f, 0.5f, .5f -.5f, -.5f, -.5f};

    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    //compile vertex shader
    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexSource, NULL);
    glCompileShader(vertexShader);

    //Compile fragment shader
    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentSource, NULL);
    glCompileShader(fragmentShader);

    //Combine shaders into a program
    GLuint shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glBindFragDataLocation(shaderProgram, 0, "outColor");
    glLinkProgram(shaderProgram);
    glUseProgram(shaderProgram);

    //retrieve a reference to the position input
    GLint posAttrib = glGetAttribLocation(shaderProgram, "position"); 
    glEnableVertexAttribArray(posAttrib);
    glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);    

    SDL_Event event;
    while (true) {
        if (SDL_PollEvent(&event)) {
            bool escape_pressed = event.type == SDL_KEYUP && 
                                   (event.key.keysym.sym == SDLK_ESCAPE);
            if (event.type == SDL_QUIT || escape_pressed) break;
            
            glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
            glClear(GL_COLOR_BUFFER_BIT);

            glDrawArrays(GL_TRIANGLES, 0, 3);

            SDL_GL_SwapWindow(window);
        }
        glDrawArrays(GL_TRIANGLES, 0, 3);

        SDL_GL_SwapWindow(window);
    }

    glDeleteProgram(shaderProgram);
    glDeleteShader(fragmentShader);
    glDeleteShader(vertexShader);
    glDeleteBuffers(1, &vbo);
    glDeleteVertexArrays(1, &vao);


    SDL_GL_DeleteContext(context);
    SDL_Quit();

    return 0;
}