To compile a shader, use the following steps:

1. Create the shader object:

GLuint vertShader = glCreateShader( GL_VERTEX_SHADER ); 
if( 0 == vertShader ) { 
  std::cerr << "Error creating vertex shader." << std::endl;
  exit(EXIT_FAILURE); 
} 

2. Copy the source code into the shader object:

std::string shaderCode = loadShaderAsString("basic.vert.glsl"); 
const GLchar * codeArray[] = { shaderCode.c_str() }; 
glShaderSource( vertShader, 1, codeArray, NULL ); 

3. Compile the shader:

glCompileShader( vertShader );

4. Verify the compilation status:

GLint result; 
glGetShaderiv( vertShader, GL_COMPILE_STATUS, &result ); 
if( GL_FALSE == result ) { 
  std::cerr << "Vertex shader compilation failed!" << std::endl;
 
  // Get and print the info log
  GLint logLen; 
  glGetShaderiv(vertShader, GL_INFO_LOG_LENGTH, &logLen); 
  if( logLen > 0 ) { 
    std::string log(logLen, ' '), 
    GLsizei written; 
    glGetShaderInfoLog(vertShader, logLen, &written, &log[0]); 
    std::cerr << "Shader log: " << std::endl << log;
  } 
}