C :

#include <stdio.h>
int main()
{
	printf("This is my first c program!");
	return 0;
}

C++ :

#include<stdio.h>
int main()
{
  printf("This is my first c program!\n");
  return 0;
}  

Pascal :

begin 
       Writeln('This is my first c program!'); 
end.

Python :

# coding=utf-8
print("This is my first c program!")