Linking a Shader results in an error of file not being read

Question

My issue begins with my shader, specifically the Vertex Shader not being linked, I am currently following the LearnOpenGL guide for the code.

ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ
ERROR::PROGRAM_LINKING_ERROR of type: PROGRAM
Vertex info
-----------
(0) : error C5145: must write to gl_Position

So this is my shader.vert file-

#version 330 core
layout (location = 0) in vec3 aPos;
void main()
{
  gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
}

A very simple, vert file I was able to achieve this working with the strings method, but when reading from file is where the issues begin.

Here is the shader.frag file -

#version 330 core
out vec4 FragColor;

in vec4 vertexColor; // the input variable from the vertex shader (same     
 name and same type)  

void main()
{
    FragColor = vertexColor;
}

This is the .h file which reads the files from LearnOpenGL, and to my knowledge this file isn't the problem.

#include <GL/glew.h>
#include <string>
#include <fstream>
#include <sstream>
#include <iostream>

class Shader
{
    public:
    unsigned int ID;
// constructor generates the shader on the fly
// ------------------------------------------------------------------------
Shader(const char* vertexPath, const char* fragmentPath)
{
    // 1. retrieve the vertex/fragment source code from filePath
    std::string vertexCode;
    std::string fragmentCode;
    std::ifstream vShaderFile;
    std::ifstream fShaderFile;
    // ensure ifstream objects can throw exceptions:
    vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
    fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
    try
    {
        // open files
        vShaderFile.open(vertexPath);
        fShaderFile.open(fragmentPath);
        std::stringstream vShaderStream, fShaderStream;
        // read file's buffer contents into streams
        vShaderStream << vShaderFile.rdbuf();
        fShaderStream << fShaderFile.rdbuf();
        // close file handlers
        vShaderFile.close();
        fShaderFile.close();
        // convert stream into string
        vertexCode = vShaderStream.str();
        fragmentCode = fShaderStream.str();
    }
    catch (std::ifstream::failure& e)
    {
        std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
    }
    const char* vShaderCode = vertexCode.c_str();
    const char* fShaderCode = fragmentCode.c_str();
    // 2. compile shaders
    unsigned int vertex, fragment;
    // vertex shader
    vertex = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex, 1, &vShaderCode, NULL);
    glCompileShader(vertex);
    checkCompileErrors(vertex, "VERTEX");
    // fragment Shader
    fragment = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment, 1, &fShaderCode, NULL);
    glCompileShader(fragment);
    checkCompileErrors(fragment, "FRAGMENT");
    // shader Program
    ID = glCreateProgram();
    glAttachShader(ID, vertex);
    glAttachShader(ID, fragment);
    glLinkProgram(ID);
    checkCompileErrors(ID, "PROGRAM");
    // delete the shaders as they're linked into our program now and no longer necessary
    glDeleteShader(vertex);
    glDeleteShader(fragment);
}
// activate the shader
// ------------------------------------------------------------------------
void use()
{
    glUseProgram(ID);
}
// utility uniform functions
// ------------------------------------------------------------------------
void setBool(const std::string& name, bool value) const
{
    glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
}
// ------------------------------------------------------------------------
void setInt(const std::string& name, int value) const
{
    glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
}
// ------------------------------------------------------------------------
void setFloat(const std::string& name, float value) const
{
    glUniform1f(glGetUniformLocation(ID, name.c_str()), value);
}

private:
// utility function for checking shader compilation/linking errors.
// ------------------------------------------------------------------------
void checkCompileErrors(unsigned int shader, std::string type)
{
    int success;
    char infoLog[1024];
    if (type != "PROGRAM")
    {
        glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
        if (!success)
        {
            glGetShaderInfoLog(shader, 1024, NULL, infoLog);
            std::cout << "ERROR::SHADER_COMPILATION_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
        }
    }
    else
    {
        glGetProgramiv(shader, GL_LINK_STATUS, &success);
        if (!success)
        {
            glGetProgramInfoLog(shader, 1024, NULL, infoLog);
            std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog << "\n - 
 - --------------------------------------------------- -- " << std::endl;
            }
        }
    }
};

I am unsure how many different ways I tried linking the files, renaming them with different names, using Full Paths, and relative Paths, and still wasn't able to find the solution.

Shader ourShader("Shaders/shader.vert","Shaders/shader.frag");

Answer 1

Alright, so after testing so many things I have found the solution:

So for linking files always have the right folder path,

Shader ourShader("Source/Shaders/Shader.vert", "Source/Shaders/Shader.frag");

Also I found that my GLEW wasn't initialized before I used this function which also led to errors, hope my solution will help to those who has the same problem.