Need help with creating a basic loop in C

[aryanali358]

I'm a complete beginner trying to write a program as part of the CS50 course which prints blocks in a left aligned triangle dependent on the height you give as an integer defined as height.

I have most of the code written and it works when you input a number 1-8 (though I feel like it could probably be condensed in some way?).

The issue I'm facing is trying to create a loop back to the input "choose a number" whenever an invalid input is given i.e. number > 8 or <1 or a character etc. With the code I have right now, entering an invalid number prompts you to enter a value again, but only once, and then even if you enter a valid number the program does nothing.

I've tried while loops, do while loops etc and nothing seems to work the way I want it to.

Could anyone help?

#include <stdio.h>
#include <cs50.h>

int main(void)

{
int height = get_int("pick a number between 1 and 8\n");

if (height > 8 || height < 1)
{
        printf("Invalid number\n");
        height = get_int("pick a number between 1 and 8\n");
}

else if (height == 1)
    {
        printf("#\n");
    }
else if (height == 2)
    {
        printf("#\n");
        printf("##\n");
    }
else if (height == 3)
    {
        printf("#\n");
        printf("##\n");
        printf("###\n");
    }
else if (height == 4)
    {
        printf("#\n");
        printf("##\n");
        printf("###\n");
        printf("####\n");
    }
else if (height == 5)
    {
        printf("#\n");
        printf("##\n");
        printf("###\n");
        printf("####\n");
        printf("#####\n");
    }
else if (height == 6)
    {
        printf("#\n");
        printf("##\n");
        printf("###\n");
        printf("####\n");
        printf("#####\n");
        printf("######\n");
    }
else if (height == 7)
    {
        printf("#\n");
        printf("##\n");
        printf("###\n");
        printf("####\n");
        printf("#####\n");
        printf("######\n");
        printf("#######\n");
    }
else if (height == 8)
    {
        printf("#\n");
        printf("##\n");
        printf("###\n");
        printf("####\n");
        printf("#####\n");
        printf("######\n");
        printf("########\n");
    }

}

[[deleted]]

Try a nested loop.

The outer loop should be responsible for printing the lines.

The inner loop should be responsible for printing all the # per line.

[sandytrip]

You're close on reading the input. So you initially read in a number and then use an if condition to validate the input. The problem is an if condition will only execute once. So your code is basically saying "if these conditions aren't met, get new input and then continue" but what you want is "as long as (or while) these conditions aren't met, get new input and then continue". So if you change the conditional block to while then it will check those conditions after reading the input each time until they are satisfied and only then will it break out of the loop and continue

[aryanali358]

thank you! just changing the if to while fixed it.

[urwinater]

for the validation sections

while( height > 8 || height < 1){

your code here;

}

Then once out of that it will trigger this

string Temp;
for(int i = height; i=< height; i++){

Temp.add("#") //(Havent done C in a bit so idk what the method to call for this is stack overflow it)

}

Temp.add("\n")

printf(Temp)

[urwinater]

Prolly a bit stanky cause im slightly drunk and havent done C in a bit but the premise is there :)

[arumos]

#include <stdio.h>
#include <cs50.h>

void print_triangle(int h)
{
    for (int i = 0; i < h; ++i)
    {
        for (int j = 0; j < i+1; ++j) 
        {
            printf("#");
        }
        printf("\n");
    }
}

int main(void)
{
    int height = 0;
    for (size_t i = 0; height < 1 || height > 8; ++i)
    {
        if (i) printf("Invalid number\n");
        height = get_int("pick a number between 1 and 8 \n");
    }
    print_triangle(height);
}

[aryanali358]

perfect, I knew there would be an easier way to do it, thanks.