CS50-Week1

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Lab1 C：Population Growth

How to do in this Lab

  1. Log into cs50 online devEnviroment
  2. Log into submitSystem
  3. When you finish any Labs,execute check50 in teminal follow the sign$
  4. After pass the check,execute style50 to decrate your code,and then submit by the command submit50.You can see practiced examples below right now.

Lab 1

Before the question

  1. Input mkdir populationto make a dir(i.e. directory) for your code by terminal.

  2. Then execute cd population to enter the dir just created,and you should see the prompt turn to population/ $ .

  3. Type wget https://cdn.cs50.net/2022/fall/labs/1/population.c from CS50 .

  4. You can have a look what inside by typing ls ,then use code population.c to start your coding.


Background

Say we have a population of n llamas. Each year, n / 3 new llamas are born, and n / 4 llamas pass away.

For example, if we were to start with n = 1200 llamas, then in the first year, 1200 / 3 = 400 new llamas would be born and 1200 / 4 = 300 llamas would pass away. At the end of that year, we would have 1200 + 400 - 300 = 1300 llamas.

To try another example, if we were to start with n = 1000 llamas, at the end of the year, we would have 1000 / 3 = 333.33 new llamas. We can’t have a decimal portion of a llama, though, so we’ll truncate the decimal to get 333 new llamas born. 1000 / 4 = 250 llamas will pass away, so we’ll end up with a total of 1000 + 333 - 250 = 1083 llamas at the end of the year.


My Thoughts

Easy to understand the question,every year the number of llamas will be plused 1/3 and at the same time mintued 1/4.

We want to know after how many years that numbern do equal the given numberm,and output the years.

After finishing the code ,time to check,debug,style and submit.

test before check in
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//How to Test Your Code
//Your program should behave per these examples below.

$ ./population
Start size: 1200
End size: 1300
Years: 1
$ ./population
Start size: -5
Start size: 3
Start size: 9
End size: 5
End size: 18
Years: 8
$ ./population
Start size: 20
End size: 1
End size: 10
End size: 100
Years: 20
$ ./population
Start size: 100
End size: 1000000
Years: 115

As soon your code works,you can check and so forth.

Following the commend below steo by step,and remember you are in the right dir.

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check50 cs50/labs/2023/x/population
style50 population.c
submit50 cs50/labs/2023/x/population

Here are my final code styled by the CS50.

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

int main(void)
{
    // TODO: Prompt for start size
    int n;
    int y = 0;
    do
    {
        n = get_int("Start size:");
    }
    while (n < 9);
    // TODO: Prompt for end size
    int m;
    do
    {
        m = get_int("End size:");
    }
    while (m < n);
    // TODO: Calculate number of years until we reach threshold
    while (n < m)
    {
        n = n + n / 3 - n / 4;
        y++;
    }
    // TODO: Print number of years
    printf("Years: %i", y);
}

Courses and other relative URLs

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