How to substitute NA by 0 in 20 columns?

Question

I want to substitute NA by 0 in 20 columns. I found this approach for 2 columns, however I guess it's not optimal if the number of columns is 20. Is there any alternative and more compact solution?

mydata[,c("a", "c")] <-
        apply(mydata[,c("a","c")], 2, function(x){replace(x, is.na(x), 0)})

UPDATE: For simplicity lets take this data with 8 columns and substitute NAs in columns b, c, e, f and d

a  b  c  d  e  f  g  d
1  NA NA 2  3  4  7  6
2  g  3  NA 4  5  4  Y
3  r  4  4  NA t  5  5

The result must be this one:

a  b  c  d  e  f  g  d
1  0  0  2  3  4  7  6
2  g  3  NA 4  5  4  Y
3  r  4  4  0  t  5  5

Answer 1

Another strategy using tidyr::replace_na()

library(tidyverse)

df <- read.table(header = T, text = 'a  b  c  d  e  f  g  h
1  NA NA 2  3  4  7  6
2  g  3  NA 4  5  4  Y
3  r  4  4  NA t  5  5')

df %>%
  mutate(across(everything(), ~replace_na(., 0)))
#>   a b c d e f g h
#> 1 1 0 0 2 3 4 7 6
#> 2 2 g 3 0 4 5 4 Y
#> 3 3 r 4 4 0 t 5 5

^{Created on 2021-08-22 by the reprex package (v2.0.0)}