What are 因 and 而 doing in the sentence 他因受到热烈欢迎而高兴?
[因 A 而 B] = [because of A, therefore B]

[因 A (受到热烈欢迎) 而 B (高兴)]
[Because of A (受到热烈欢迎), Therefore B (高兴)]

or

[B because of A] ; [B for A]
[B (高兴) because of A (受到热烈欢迎)]
[B (高兴) for A (受到热烈欢迎)]

When A is a reason; B is an action
When A is a cause; B is a result