lab4,5 fix

golang/internal/lab4/lab4.go

@@ -5,7 +5,7 @@ import (
 )
 
 func Task1(a, b, xn, xk, deltax float64) []float64 {
-	var answers1 []float64 = make([]float64, 0)
+	var answers1 []float64 = make([]float64, 0, int((xk - xn)/deltax) + 1)
 	for x := xn; x <= xk; x += deltax {
 		y := (a + math.Pow(math.Tan(b*x), 2)) / (b + math.Pow(math.Atan(a*x), 2))
 		answers1 = append(answers1, y)
@@ -14,7 +14,7 @@ func Task1(a, b, xn, xk, deltax float64) []float64 {
 }
 
 func Task2(a float64, b float64, znX []float64) []float64 {
-	var answers2 []float64 = make([]float64, 0)
+	var answers2 []float64 = make([]float64, 0, len(znX))
 	for _, x := range znX {
 		y := (a + math.Pow(math.Tan(b*x), 2)) / (b + math.Pow(math.Atan(a*x), 2))
 		answers2 = append(answers2, y)

golang/internal/lab5/lab5.go

@@ -2,6 +2,7 @@ package lab5
 
 import (
 	"fmt"
+	"errors"
 )
 
 type city struct {
@@ -13,11 +14,17 @@ func (c city) GetPopulation() int {
 	return c.population
 }
 
-func NewCity(setPopulation int, setCountry string) city {
-	return city{
+func NewCity(setPopulation int, setCountry string) (*city, error) {
+	c := &city{
 		population: setPopulation,
 		country:    setCountry,
 	}
+
+	if err := c.SetPopulation(setPopulation); err != nil {
+		return nil, err
+	}
+
+	return c, nil
 }
 
 func (c *city) SetCountry(country string) {
@@ -29,7 +36,7 @@ func (c *city) SetPopulation(population int) error {
 		c.population = population
 		return nil
 	}
-	return fmt.Errorf("invalid city population")
+	return errors.New("invalid city population")
 }
 
 func (c city) GetCountry() string {

golang/main.go

@@ -2,18 +2,11 @@ package main
 
 import (
 	"fmt"
-	"log"
 
 	"isuct.ru/informatics2022/internal/lab4"
 	"isuct.ru/informatics2022/internal/lab5"
 )
 
-func checkForError(err error) {
-	if err != nil {
-		log.Fatal(err)
-	}
-}
-
 func main() {
 	fmt.Println("Махотина Валерия Олеговна")
 	fmt.Println("---")
@@ -24,14 +17,13 @@ func main() {
 	a2 := lab4.Task2(0.1, 0.5, []float64{0.2, 0.3, 0.44, 0.6, 0.56})
 	fmt.Println(a2)
 
-	var city = lab5.NewCity(400, "Russia")
+	city, err := lab5.NewCity(400, "Russia")
 
-	var err error = city.SetPopulation(400)
-	checkForError(err)
-
-	city.SetCountry("Russia")
-
-	fmt.Printf("City's population is %d\n", city.GetPopulation())
-	fmt.Printf("This city is in %s\n", city.GetCountry())
-	city.GetTheCity()
+	if err == nil{
+		fmt.Printf("City's population is %d\n", city.GetPopulation())
+		fmt.Printf("This city is in %s\n", city.GetCountry())
+		city.GetTheCity()
+	} else {
+		fmt.Println(err)
+	}
 }