Quality Inns International of Silver Spring reported yesterday its domestic operations were in the black for the first half of the fiscal year, but the company lost $1.8 million because of foreign operations and the weakness of the dollar in foreign exchange.

The 300-unit hotel and motel chain said its U.S. business, which recorded a $1.07 million loss in the first half of 1977, showed a $127,000 profit for that period this year.

Losses of foreign hotels were cut from $730,000 to $569,000, But a $1.2 million loss from currency translations left Qualify Inns with an overall loss of $1.7 million (68 cents a share) compared with $1.6 million (63 cents) in 1977.

Revenues for the first half increased from $24 million to $25.8 million, while second-quarter revenues went from $11.3 million to $12.1 million. For the three months ended Feb. 28, the company's loss grew from $1.7 million (65 cents).

Saying "Quality Inns is in the soundest financial position is has experienced in recent years," Chairman Joseph W. McCarthy blamed the larger loss on the currency translations, which he said "had a tremendous and misleading effect." The company's revenues in foreign currency must be translated into dollars, resulting in paper losses because of the declining value of the dollar.

Smithfield Foods Inc., a Virginia meat processer, reported net income of $2.1 million (84 cents a share) for the year ended Jan.1 compared with $1.5 million (59 cents) for the previous year.

Smithfield Foods Inc., a Virginia $1.5 million from continuing operations and $598,000 from discontinued business - the Family Fish Houses chain which was sold in January to the Macke Co. of Washington. A $2.7 million gain from the sale will be reported in the first quarter of 1978.

Annual sales from continuing opertions increased from $131 million to $139 million.

Smithfield earned $830,000 (32 cents) in the fourth quarter compared with $1.03 million (39 cents) the pior year.

NUS Corp. of Rockville reported it turned its 1976 loss of $133,000 into a $1.3 million profit in 1977, while its revenues increased from $24 million to $34 million.

The turnaround, from a 13 cent-per-share loss to a $1.28 profit, was attributed to greater diversity in both the services and markets of NUS, an energy and environmental consulting firm that works mostly for electric utilities.

For the fourth quarter of 1977, NUS reported earnings of $304,000 (31 cents a share) on revenues of $10 million compared with a loss of $154,000 (15 cents) on revenues of $6 million.

A spokesman said fourth-quarter earnings were reduced 29 cents a share by overruns and reserves on five fixed-price contracts and by a $95,000 write-off for terminating an agreement to merge with Halliburton Co.

Neither factor is expected to hurt future earnings of the company, which said its yearend backlog of contracts has grown from $1.5 million in 1976 to $21.8 million.