Clearing memory after loading shaders - c++

Question

Although I do the suggested steps, I get a memory leak. I load and delete shaders as follows:
glCreateShader
glShaderSource
glCompileShader
glAttachShader
glLinkProgram
glUseProgram
glDetachShader
glDeleteShader
glUseProgram(0);
glDeleteProgram
glLingProgram() seems to cause the leak when I do all these steps in a loop. Below is my test code. Could you please help me find out the problem? (The code is based on the tutorials on http://opengl-tutorial.org/).
EDIT: I think this occurs only when the vertex shader includes an attribute type.
for (int i = 0; i < 1000; i++) {
GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
std::string VertexShaderCode;
std::ifstream VertexShaderStream("VertexShader.vs", std::ios::in);
if(VertexShaderStream.is_open()) {
std::string Line = "";
while(getline(VertexShaderStream, Line))
VertexShaderCode += "\n" + Line;
VertexShaderStream.close();
}
else {
printf("Cannot open vertex shader!");
getchar();
return 0;
}
std::string FragmentShaderCode;
std::ifstream FragmentShaderStream("FragmentShader.fs", std::ios::in);
if(FragmentShaderStream.is_open()) {
std::string Line = "";
while(getline(FragmentShaderStream, Line)) {
FragmentShaderCode += "\n" + Line;
}
FragmentShaderStream.close();
}
else {
printf("Cannot open fragment shader!");
getchar();
return 0;
}
char const * VertexSourcePointer = VertexShaderCode.c_str();
glShaderSource(VertexShaderID, 1, &VertexSourcePointer , NULL);
glCompileShader(VertexShaderID);
char const * FragmentSourcePointer = FragmentShaderCode.c_str();
glShaderSource(FragmentShaderID, 1, &FragmentSourcePointer , NULL);
glCompileShader(FragmentShaderID);
GLuint ProgramID = glCreateProgram();
glAttachShader(ProgramID, VertexShaderID);
glAttachShader(ProgramID, FragmentShaderID);
glLinkProgram(ProgramID);
glUseProgram(ProgramID);
glDetachShader(ProgramID, VertexShaderID);
glDetachShader(ProgramID, FragmentShaderID);
glDeleteShader(VertexShaderID);
glDeleteShader(FragmentShaderID);
glUseProgram(0);
glDeleteProgram(ProgramID);
}

Answer 1

You should load the shaders only at the beginning. Only glUseProgram is intended to be used in the render loop.
Standard template of using a shader is like this:
glCreateProgram
glCreateShader
glShaderSource
glCompileShader
glAttachShader
glLinkProgram <- after this line opengl got everything it needs,
you can free shader resources
glDetachShader
glDeleteShader
for{//render loop
glUseProgram
//...drawing operations
glUseProgram(0);
}
glDeleteProgram