How to set user permissions programmatically?

    1: SPSite site = null;

    2: SPWeb web = null;

    3: site = new SPSite("https://server:100/sites/DevSite/");

    4: web = site.OpenWeb();

    5: SPRoleAssignment roleAssignment = new SPRoleAssignment("domain\\user","alias@domain.com","Nishand","Simple Test For You!");

    6: SPRoleDefinition roleDefinition = web.RoleDefinitions.GetByType(SPRoleType.Contributor);

    7: roleAssignment.RoleDefinitionBindings.Add(roleDefinition);

    8: web.RoleAssignments.Add(roleAssignment); 

 

Enjoy!!!