word wrap long character string inside div tag

I have a DIV container I'm using as a comment box. I want to make sure that text doesn't overflow the DIV container, and instead 开发者_如何学JAVAwill wrap a long word. What's the easiest way to do this with CSS and PHP?

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apply the below class to div

.break-word {
  word-wrap: break-word;
}

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define white-space:normal; as css property to div to fit text in box and to break word is word-wrap:break-word;