西江夜行张九龄古诗的全文及翻译如下：平生不会相思，才会相思，便害相思。身如明月几时有，把相思灯下诉。而今相思只一种，愿得一心人，白头不相离，日日两相思。
西江夜行张九龄古诗的全文及翻译如下：
平生不会相思，
才会相思，便害相思。
身如明月几时有，
把相思灯下诉。
而今相思只一种，
愿得一心人，
白头不相离，
日日两相思。
Translation:
Throughout my life, I did not understand what it meant to long for someone,
But now that I've experienced it, the longing tortures me.
Just like the appearance of a full moon, it is fleeting,
Yet I express my longing under the light of a solitary lamp.
Nowadays, there is only one kind of longing in my heart,
I hope to find someone who shares the same sentiment,
Growing old together and never parting,
Every day filled with mutual longing.