PARIS — In France on Sunday, the flan was decidedly in the oven, while the tomato was surprisingly green. By the same token — according to Twitter, at any rate — the temperature in Budapest hovered near 25 degrees.

French law prohibits the publication, by the media or any Internet-connected citizen, of voting results or estimates before 8 p.m. on election days in the presidential race. The best-laid plans could not stop Twitter, though, whose users skirted regulations with offbeat code words and communicated tallies ahead of the appointed hour on Sunday.

The flan stood for François Hollande, the Socialist favorite, who finished the evening in the lead, with about 28 percent of the votes in the first of two rounds of voting. (Before losing weight for his presidential bid, the jovial Mr. Hollande had been known in some circles as “Flanby,” a brand of jiggly French custard.)

The tomato was the far-left candidate Jean-Luc Mélenchon, whose Left Front party was largely composed of communists — thus the red fruit reference. He finished with a disappointing 11 percent.