/* HEADER FILES */
#include <stdio.h>
#include <conio.h>
#include <string.h>

/* The char "c1" and "c2" are initialized in order that not affect the thousands */
char *a2roman (int value, char *c1, char *c2, char *c3);

int main (void)
{
    int arabicalNumeral = 1; /* Initialization for read althought one time  */
    int result;              /* "result" store the position value           */
    char roman[15] = "";     /* "roman" contain the roman-numeral string    */

    /* This cicle allow to continue if "arabicalNumber" to be in the range */
    do
    {
        /* Clear the screen */
        clrscr();

        /* Print a message to user */
        printf ("Enter a integer in 1 to 3000 range of integers: \n\t");

        /* Read the value */
        scanf ("%d", &arabicalNumeral);
    }
    while ((arabicalNumeral < 1) || (arabicalNumeral > 3000));

    /* Obtain the value of thousands */
    if ((arabicalNumeral <= 3000) && (arabicalNumeral >= 1000))
    {
        result = arabicalNumeral / 1000;
        strcat (roman, a2roman(result, "M", " ", " "));
        arabicalNumeral -= (result * 1000);
    }

    /* Obtain the value of hundreds */
    if ((arabicalNumeral < 1000) && (arabicalNumeral >= 100))
    {
        result = arabicalNumeral / 100;
        strcat (roman, a2roman(result, "C", "D", "M"));
        arabicalNumeral -= (result * 100);
    }

    /* Obtain the value of tens */
    if ((arabicalNumeral < 100) && (arabicalNumeral >= 10))
    {
        result = arabicalNumeral / 10;
        strcat (roman, a2roman(result, "X", "L", "C"));
        arabicalNumeral -= (result * 10);
    }

    /* Obtain the value of units */
    if ((arabicalNumeral < 10) && (arabicalNumeral >= 1))
    {
        strcat (roman, a2roman(arabicalNumeral, "I", "V", "X"));
    }

    /* Display the Roman numeral */
    printf ("The Roman numeral is: \n\t%s\n\n", roman);
    printf ("\t\t      ...Press any key to exit.");
    getch();

    /* Succesfull return */
    return 0;
}

char *a2roman (int value, char *c1, char *c2, char *c3)
{
    int i;    /* "i" is the index of the iteration */
    char rRoman[15] = "";

    /* If value = 1, 2, 3 */
    if ((value >= 1) && (value <= 3))
    {
        for (i = 0; i < value; i++)
            strcat (rRoman, c1);
    }

    /* If value = 5, 6, 7, 8 */
    if ((value >= 5) && (value <= 8))
    {
        strcat (rRoman, c2);

        for (i = 0; i < (value - 5); i++)
            strcat (rRoman, c1);
    }

    /* If value = 4 */
    if (value == 4)
    {
        strcat (rRoman, c1);
        strcat (rRoman, c2);
    }

    /* If value = 9 */
    if (value == 9)
    {
        strcat (rRoman, c1);
        strcat (rRoman, c3);
    }

    return (rRoman);
}

char str1[20];   //pretend it already has a value
char str2[20];   //same here
char concated[40];    //where the concated string will go
int x;

for(x = 0; x < strlen(str1); x++)
  concated[x] = str1[x];  //adds the first string to concated

for(x = 0; x < strlen(str2); x++)
  concated[x + strlen(str1)] = str2[x];  //adds the second string