Code Snippet: Print All Integers in a String

Within these castle walls be forged Mavens of Computer Science ...

— Merlin, The Coder

Print All Digits in a String

Swift

let text = "ab3bk49dn3"
for character in text {
    if ("0"..."9").contains(character) {
        print(character)
    }
}

Python

text = 'ab3bk49dn3'
for character in text:
    if character.isdigit():
        print(character)

Java

String text = "ab3bk49dn3";
for (char character : text.toCharArray()) {
    if (Character.isDigit(character)) {
        System.out.println(character);
    }
}

// This is not the best code but it is easy to understand

String s = "ab3bk49dn3"; // random string
String sAsInt = ""; // string that will contain the numbers from s in order
char[] numArray = {'0','1','2','3','4','5','6','7','8','9'}; // array with numbers as chars

// Loop through all the chars to find the numbers
for(char character: s.toCharArray()) {
   for(char digit: numArray) {
      if(character == digit) sAsInt += x + ""; // add the digit on to the end of sAsInt
   }
}

Print All Digits from Standard Input

Swift

var line : String?
repeat {
    line = readLine()
    if let text = line {
        for character in text {
            if ("0"..."9").contains(character) {
                print(character)
            }
        }
    }
} while line != nil

Python

line = input()
for char in line:
    if char.isdigit():
        print(char)

Source

Java

Scanner scanner = new Scanner(System.in);
while (scanner.hasNextLine()) {
    for (char character : scanner.nextLine().toCharArray()) {
        if (Character.isDigit(character)) {
            System.out.println(character);
        }
    }
}

C

#include <stdio.h>
#include <ctype.h>
#include <string.h>

int main( void ) {
  char *line;
  fgets(line, 255, stdin);

  size_t line_length = strlen(line);

  for (size_t i = 0; i < line_length; i++) {
    if (isdigit(line[i])) {
      printf("%c\n",line[i]);
    }
  }

  return 0;
}