fork download 
  1. x <- c("foo bar", "foo")
  2. grep("(?s)foo(?!.*bar)", x, perl=TRUE, value=TRUE)
Success #stdin #stdout 0.23s 39284KB
comments (?)
stdin 
Standard input is empty
stdout 
[1] "foo"
https://ideone.com/IYPbGU
language:
R (R 3.5.2)
created:
7 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!