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

int main(int argc, char *argv[]){
  char caractere;

  // vamos ler o caractere informado pelo usuário
  printf("Informe um caractere e tecle ENTER: ");
  scanf("%c", &caractere);

  // vamos verificar se o usuário informou um dígito
  // de 0 a 9
  if(isdigit(caractere))
    printf("Voce informou um digito de 0 a 9");
  else
    printf("Voce NAO informou um digito de 0 a 9");

  puts("\n\n");
  system("PAUSE");
  return 0;
}

<?php
  $valor = 4;
  
  switch($valor){
    case 0:
      echo "Valor é igual a 0";
      break;
    case 1:
      echo "Valor é igual a 1";
      break;
    case 2:
      echo "Valor é igual a 2";
      break;
    default:
      echo "Nenhuma das anteriores";
  }
?>

# função principal do programa
def main():
  # vamos pedir para o usuário informar a medida em pés
  pes = float(input("Informe a medida em pés: "))

  # agora vamos converter a medida em pé para metros
  metros = 0.3048 * pes

  # e mostramos o resultado
  print("A medida em metros é: {0}m".format(metros))
  
if __name__== "__main__":
  main()

Package           Version
----------------- -------
astroid           2.4.2
colorama          0.4.4
isort             5.6.4
lazy-object-proxy 1.4.3
mccabe            0.6.1
numpy             1.19.4
pandas            1.1.5
Pillow            8.0.1
pip               20.2.3
pylint            2.6.0
python-dateutil   2.8.1
pytz              2020.4
setuptools        49.2.1
six               1.15.0
toml              0.10.2
wrapt             1.12.1
wxPython          4.1.1

# importamos a bibliteca Pandas
import pandas as pd

def main():
  # vamos mostrar a versão da biblioteca Pandas
  versao = pd.__version__

  print("A versão do Pandas é:", versao)

if __name__== "__main__":
  main()

Exception has occurred: ModuleNotFoundError
No module named 'pandas'
  File "C:\estudos_python\estudos.py", line 2, in <module>
    import pandas as pd

Collecting pandas
  Downloading pandas-1.1.5-cp39-cp39-win_amd64.whl (8.9 MB)
     |-| 8.9 MB 1.7 MB/s
Collecting numpy>=1.15.4
  Downloading numpy-1.19.4-cp39-cp39-win_amd64.whl (13.0 MB)
     |-| 13.0 MB 3.3 MB/s
Collecting pytz>=2017.2
  Downloading pytz-2020.4-py2.py3-none-any.whl (509 kB)
     |-| 509 kB 6.4 MB/s
Collecting python-dateutil>=2.7.3
  Downloading python_dateutil-2.8.1-py2.py3-none-any.whl (227 kB)
     |-| 227 kB 3.2 MB/s
Requirement already satisfied: six>=1.5 in 
c:\users\osmar\appdata\roaming\python\python39\site-packages
 (from python-dateutil>=2.7.3->pandas) (1.15.0)
Installing collected packages: numpy, pytz, 
python-dateutil, pandas
Successfully installed numpy-1.19.4 pandas-1.1.5 
python-dateutil-2.8.1 pytz-2020.4
WARNING: You are using pip version 20.2.3; however, 
version 20.3.1 is available.
You should consider upgrading via the 'c:\python_3_9_1\python.exe -m pip install 
--upgrade pip' command.