Walmart posted fiscal second-quarter results that surpassed Wall Street's expectations, and the retail giant raised its full-year guidance.

Walmart on Wednesday reported adjusted earnings of 81 cents a share for the quarter ended July 31, up from 68 cents a share a year earlier and topping the 74 cents a share that analysts polled by FactSet, on average, had been expecting.

The Bentonville, Ark., company said revenue rose 5.9% to $187.9 billion, ahead of the $186.6 billion analysts had penciled in.

Walmart said it now expects full-year adjusted earnings of $2.80 to $2.87 a share, up from a prior forecast of $2.75 to $2.85 a share.

The company added that it expects full-year sales to rise by 4% to 5% in constant currency, up from prior guidance of 3.5% to 4.5%.