Product of character vector and binary number vectors in R

Question

I have one character vectors and one binary number vectors like:

char <- paste("item", 1:4, sep="")
bnum <- c(1, 0, 0, 1)

And i would like to have a result like belows:

[1] "item1" 0 0 "item4"

Indeed my ultimate goal is to generate:

[1] "item1-item4"

And i suppose task one generate vector "ans", then the code for second task would be:

ans<- c("item1",0,0,"item4","item5")
ans2<-ans[ans!=0]
n<-length(ans2)
ans3<-ans2[1]
for (i in 2:n){
    ans3 <- paste(ans3,ans2[i],sep="-")
}

Thanks for your help.

Answer 1

char[as.logical(bnum)]

paste(char[as.logical(bnum)], collapse="-")
#[1] "item1-item4"

Answer 2

char <- paste("item", 1:4, sep="")
bnum <- c(1, 0, 0, 1)

paste(char[bnum == 1], collapse = '-')