Question

Hello wrote a program that outprints this;

0

01

012

0123

01234

012345

01234

0123

012

01

0

Im pretty sure my method is long and stupid, heres how it looks like

#include <stdio.h>

int main(void)
{

int first = -1, second = -1, third = -1, fourth = -1, fifth = -1, sixth = -1, seventh = -1, eight = -1, nine = -1, ten = -1, elleven = -1;

while(first < 0){
first += 1; 
printf("%d\n", first);

while(second < 1){
second += 1;
printf("%d", second);
}
printf("\n");
while(third < 2 ){
third += 1;
printf("%d", third);
}
printf("\n");
while(fourth < 3){
fourth += 1;
printf("%d", fourth);
}
printf("\n");
while(fifth < 4){
fifth += 1;
printf("%d", fifth);
}
printf("\n");
while(sixth < 5){
sixth += 1;
printf("%d", sixth);
}
printf("\n");
while(seventh < 4){
seventh += 1;
printf("%d", seventh);
}
printf("\n");
while(eight < 3){
eight += 1;
printf("%d", eight);
}
printf("\n");
while(nine < 2) {
nine += 1;
printf("%d", nine);
}
printf("\n");
while(ten < 1){
ten += 1;
printf("%d", ten);
}
printf("\n");
while(elleven < 0){
elleven += 1;
printf("%d", elleven); 
}
}

return 0;
}

if anyone would be kind enough to show me how to do this easier? 🙂

Answer 1

Well, I notice that you have a string whose length varies from 1 to 6, and then back, containing the symbols from 0 to its length excluded.

So we can do this with two loops, one ascending, one descending, both nested to get all symbols.

    int i, j;

    for (i = 0; i < 6; i++)
    {
            for (j = 0; j <= i; j++)
                    printf("%d", j);
            printf("\n");
    }
    for (i = 5; i > 0; i--)
    {
            for (j = 0; j < i; j++)
                    printf("%d", j);
            printf("\n");
    }

The second for may be replaced with while(--i), since i starts from the end of the previous cycle.

Output:

0
01
012
0123
01234
012345
01234
0123
012
01
0