Using vertex attributes for GLSL with LibiGL - c++

Question

I am doing some computationally heavy stuff on meshes with libiGL(c++) and am trying to move these computations over to the GPU. To start off, I am trying to get a basic piece of code running but the attribute values do not seem to get passed on to the shaders.
int m = V.rows();//vertices
P.resize(m);
for (int i = 0; i < m; i++)
{
P(i) = i / m;
}
std::map<std::string, GLuint> attrib;
attrib.insert({ "concentration", 0 });
igl::opengl::create_shader_program(
mesh_vertex_shader_string,
mesh_fragment_shader_string,
attrib,
v.data().meshgl.shader_mesh);
GLuint prog_id = v.data().meshgl.shader_mesh;
const int num_vert = m;
GLuint vao[37 * 37];//37*37 vertices
glGenVertexArrays(m, vao);
GLuint buffer;
for (int i = 0; i < m; i++)
{
glGenBuffers(1, &buffer);
glBindVertexArray(vao[i]);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(float), P.data(), GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 1, GL_FLOAT, GL_FALSE, 0, (void*)(i*sizeof(float)));
}
The red color of each vertex should be dependant on its ordering (from 0 red to 1 red) but instead the mesh is colored with no red at all.
I am basing myself off of this code :https://github.com/libigl/libigl/issues/657 and http://www.lighthouse3d.com/cg-topics/code-samples/opengl-3-3-glsl-1-5-sample/.
I modified the shader strings accordingly by adding the following lines:
Vertex Shader
in float concentration;
out float c;
c = concentration;
where the last line is in main();
Fragment Shader
in float c;
outColor.x = c;
where the last line is in main().
What am I doing wrong?
Edit: OpenGL version used is actually 3.2