C Program to Convert Numbers to Roman Numerals

August 14, 2016

C Program to Convert Numbers to Roman Numerals.

```
#include <stdio.h>
```
```
 
```
```
void predigit(char num1, char num2);
```
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void postdigit(char c, int n);
```
```
 
```
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char romanval[1000];
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int i = 0;
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int main()
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{
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    int j;
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    long number;
```
```
 
```
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    printf("Enter the number: ");
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    scanf("%d", &number);
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    if (number <= 0)
```
```
    {
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        printf("Invalid number");
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        return 0;
```
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    }
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    while (number != 0)
```
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    {
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        if (number >= 1000)
```
```
        {
```

            postdigit('M', number / 1000);

            number = number - (number / 1000) * 1000;

```
        }
```
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        else if (number >= 500)
```
```
        {
```

            if (number < (500 + 4 * 100))

```
            {
```

                postdigit('D', number / 500);

                number = number - (number / 500) * 500;

```
            }
```
```
            else
```
```
            {
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```
                predigit('C','M');
```

                number = number - (1000-100);

```
            }
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```
        }
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        else if (number >= 100)
```
```
        {
```

            if (number < (100 + 3 * 100))

```
            {
```

                postdigit('C', number / 100);

                number = number - (number / 100) * 100;

```
            }
```
```
            else
```
```
            {
```
```
                predigit('L', 'D');
```

                number = number - (500 - 100);

```
            }
```
```
        }
```
```
        else if (number >= 50 )
```
```
        {
```
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            if (number < (50 + 4 * 10))
```
```
            {
```

                postdigit('L', number / 50);

                number = number - (number / 50) * 50;

```
            }
```
```
            else
```
```
            {
```
```
                predigit('X','C');
```

                number = number - (100-10);

```
            }
```
```
        }
```
```
        else if (number >= 10)
```
```
        {
```
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            if (number < (10 + 3 * 10))
```
```
            {
```

                postdigit('X', number / 10);

                number = number - (number / 10) * 10;

```
            }
```
```
            else
```
```
            {
```
```
                predigit('X','L');
```

                number = number - (50 - 10);

```
            }
```
```
        }
```
```
        else if (number >= 5)
```
```
        {
```
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            if (number < (5 + 4 * 1))
```
```
            {
```

                postdigit('V', number / 5);

                number = number - (number / 5) * 5;

```
            }
```
```
            else
```
```
            {
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```
                predigit('I', 'X');
```

                number = number - (10 - 1);

```
            }
```
```
        }
```
```
        else if (number >= 1)
```
```
        {
```
```
            if (number < 4)
```
```
            {
```

                postdigit('I', number / 1);

                number = number - (number / 1) * 1;

```
            }
```
```
            else
```
```
            {
```
```
                predigit('I', 'V');
```

                number = number - (5 - 1);

```
            }
```
```
        }
```
```
    }
```
```
    printf("Roman number is: ");
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    for(j = 0; j < i; j++)
```
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        printf("%c", romanval[j]);
```
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    return 0;
```
```
}
```
```
 
```
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void predigit(char num1, char num2)
```
```
{
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    romanval[i++] = num1;
```
```
    romanval[i++] = num2;
```
```
}
```
```
 
```
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void postdigit(char c, int n)
```
```
{
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```
    int j;
```
```
    for (j = 0; j < n; j++)
```
```
        romanval[i++] = c;
```
```
}
```

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