gistfile1.txt

#include <stdio.h>

#define LENGTH 99
#define MISSING_NUMBER 47

int main()
{
        // vars
        int numbers[LENGTH];
        int missingnumber = -1;
        int i;

        // create array-o-numbers
        for (i=0; i<MISSING_NUMBER; i++)
                numbers[i]=i;
        for (i=MISSING_NUMBER+1; i<LENGTH; i++)
                numbers[i]=i;

        // find missing number
        i = 0;
        while(i < LENGTH-1)
        {
                if( numbers[i+1]-numbers[i] > 1)
                {
                        missingnumber = i;
                        break;
                }
                i++;
        }

        // test
        if( missingnumber == MISSING_NUMBER )
                printf("Missing number found successfully!\n");
        else
                printf("ERROR! Expecting: %i, Found: %i\n",MISSING_NUMBER,missingnumber);

        return 0;
}