How to use R gather the coordinate data of the grid which has pixel values are 0 in a map

I have a raster map with 202 rows and 201 columns there are some grids in this map which pixel values is 0 I want to write a function that return all the pixel values 0 grids' coordinate how can I do it I was trying to use if loop and while loop but it always says TRUE/FALSE need here is my sample code

library(raster)
library(rgdal)
library(maptools)
library(sp)


setwd("E:/Landsat-data-NASA atm-corrected/sample_day1")
restdir2 <- ("E:/Landsat-data-NASA atm-corrected/sample_day1")
  n3 <- list.files(restdir2, pattern="*band4_clip_1.tif", full.names=TRUE)
  n4 <- list.files(restdir2, pattern="*cloud_qa_clip_1.tif", full.names=TRUE)
  n5 <- list.files(restdir2, pattern="*cloud.tif", full.names=TRUE)

create<- function(x,y)
{
 layer <- raster(n4)
 layer2 <- raster(n3)
   for(c in 1:x)
  {
    for(r in 1:y)
   {      
       nl<- layer2
       if(layer[c,r]==0)
       return layer[c,r]
   }
  }
}
create (10,10)