Extract the First 2 Characters in a String

Extract the first 2 Characters in a string

You can just use the substr function directly to take the first two characters of each string:

x <- c("75 to 79", "80 to 84", "85 to 89")
substr(x, start = 1, stop = 2)
# [1] "75" "80" "85"

You could also write a simple function to do a "reverse" substring, giving the 'start' and 'stop' values assuming the index begins at the end of the string:

revSubstr <- function(x, start, stop) {
  x <- strsplit(x, "")
  sapply(x, 
         function(x) paste(rev(rev(x)[start:stop]), collapse = ""), 
         USE.NAMES = FALSE)
}
revSubstr(x, start = 1, stop = 2)
# [1] "79" "84" "89" 

How to get the first 2 letters of a string in Python?

It is as simple as string[:2]. A function can be easily written to do it, if you need.

Even this, is as simple as

def first2(s):
    return s[:2]

Extract first two characters of a String in Java

Your code looks great! If you wanted to make it shorter you could use the ternary operator:

public String firstTwo(String str) {
    return str.length() < 2 ? str : str.substring(0, 2);
}

How to extract the first X characters of a string and use them into another in C

You are missing the string's NUL terminator '\0' so it keeps printing until it finds one.
Declare it like:

char  pre_salt[3]={0,0,0};

And problem solved.

Extract the first (or last) n characters of a string

See ?substr

R> substr(a, 1, 4)
[1] "left"

extract the first two characters from a list of names in r

We can use str_extract_all to extract two characters after the word boundary

library(stringr)
library(dplyr)
library(purrr)
df1 %>%
     mutate(two_chars = str_extract_all(list_names, "\\b[a-z]{2}")  %>%
                            map_chr(toString))
#  id                                    list_names                  two_chars
#1  1                                          john                         jo
#2  2                                   adam, sally                     ad, sa
#3  3                                       rebecca                         re
#4  4                          zhang, mike, antonio                 zh, mi, an
#5  5 mark, henry, scott, john, steve, jason, nancy ma, he, sc, jo, st, ja, na

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Or using gsub

gsub("\\b([a-z]{2})[^,]+", "\\1", df1$list_names)
#[1] "jo"                         "ad, sa"                     "re"                         "zh, mi, an"                
#[5] "ma, he, sc, jo, st, ja, na"

Get First 2 Characters In a String

Second arg should be $s, see printf()

printf("[%0.2s]\n", $s);

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