In R, we use the grepl() function to check if characters are present in a string or not. And the method returns a Boolean value,
TRUE- if the specified sequence of characters are present in the stringFALSE- if the specified sequence of characters are not present in the string
Example: Check if Character is Present in a String in R
string1 <- "Programiz"
value1 <- "miz"
# check if "miz" is present in "Programiz"
grepl(value1, string1)  # TRUE
value2 <- "grm"
# check if "grm" is present in "Programiz"
grepl(value2, string1)  # FALSE
Output
[1] TRUE [2] FALSE
In the above example, we have used the grepl() function to check if a sequence of characters is present in a string or not. Notice the code,
grepl(value1, string1) 
Here, grepl() takes two arguments
- value1 - sequence of characters to be searched
 - string1 - a string in which value1 is searched
 
Similarly, value2 is searched in string1.
Since
"miz"is present in"Programiz", the function returnsTRUE"grm"is not present in"Programiz", the function returnsFALSE