json.R

#delete the next # if rjson package is not installed in the system
#install.packages("rjson")
library("rjson")

#load from a json file
data=fromJSON(file="E:/test.json")

#check the data
print(data)

##dump the variable as a file
#write(toJSON(data),file="E:/test.json")

json_result.R

> #check the data
> print(data)
$A
[1] 10

$C
[1] 30 40

$B
[1] 20