cpp-httplib v0.42.0
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C03. Set Default Headers

When you want the same headers on every request, use set_default_headers(). Once set, they're attached automatically to every request sent from that client.

Basic usage

httplib::Client cli("https://api.example.com");

cli.set_default_headers({
  {"Accept", "application/json"},
  {"User-Agent", "my-app/1.0"},
});

auto res = cli.Get("/users");

httplib::Client cli("https://api.example.com");

cli.set_default_headers({
  {"Accept", "application/json"},
  {"User-Agent", "my-app/1.0"},
});

auto res = cli.Get("/users");

Register the headers you need on every API call — like Accept or User-Agent — in one place. No need to repeat them on each request.

Send a Bearer token on every request

httplib::Client cli("https://api.example.com");

cli.set_default_headers({
  {"Authorization", "Bearer " + token},
  {"Accept", "application/json"},
});

auto res1 = cli.Get("/me");
auto res2 = cli.Get("/projects");

httplib::Client cli("https://api.example.com");

cli.set_default_headers({
  {"Authorization", "Bearer " + token},
  {"Accept", "application/json"},
});

auto res1 = cli.Get("/me");
auto res2 = cli.Get("/projects");

Set the auth token once, and every subsequent request carries it. Handy when you're writing an API client that hits multiple endpoints.

Note: set_default_headers() replaces the existing default headers. Even if you only want to add one, pass the full set again.

Combine with per-request headers

You can still pass extra headers on individual requests, even with defaults set.

httplib::Headers headers = {
  {"X-Request-ID", "abc-123"},
};
auto res = cli.Get("/users", headers);

httplib::Headers headers = {
  {"X-Request-ID", "abc-123"},
};
auto res = cli.Get("/users", headers);

Per-request headers are added on top of the defaults. Both are sent to the server.

For details on Bearer token auth, see C06. Call an API with a Bearer token.

ESC