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I’m thinking the same thing! I could be wrong but i’d swear there is no explanation (or not sufficiently explicit) for the use of scanf() prior to this exercise.
This was a very strange lesson. I don’t remember being introduced to neither the scanf() function nor to the argument “&x”, which the hint suggested. Furthermore it says the lesson is optional, but I couldn’t click “up next” without solving the exercise, which meant I ended up just copying the hint.
You don’t need currentWeight because you don’t need to save earthWeight, just use earthWeight = eatrhWeight * planet weight.
Also, you can printf weight inside switch case for example for case 7 :
case 7:
printf(“Your current weight on Neptune is: %f\n”, earthWeight * 1.19);
break;
It’s ok, but you don’t need to type weight for every planet. Just make variable weight and multiply it with planet constant.
For example :
if (numberPlanet = 1){
printf(“Mercury: %f\n”, weight0.38);
}
else if (numberPlanet = 2){
printf(“Venus: %f\n”, weight0.91);
}
etc.
I don’t know why you don’t include return value at the end of the function because main function is int ?
Here is my solution :
#include <stdio.h>
int main() {
double weight;
int planet;
printf(“Enter the weight: “);
scanf(”%lf”,&weight);
printf(“Enter the planet from 1-7: “);
scanf(”%d”,&planet);
switch (planet) {
case 1:
printf(“Your weight on Mercury is %.2lf\n”,weight0.38);
break;
case 2:
printf(“Your weight on Venus is %.2lf\n”,weight0.91);
break;
case 3:
printf(“Your weight on Mars is %.2lf\n”,weight0.38);
break;
case 4:
printf(“Your weight on Jupiter is %.2lf\n”,weight2.34);
break;
case 5:
printf(“Your weight on Saturn is %.2lf\n”,weight1.06);
break;
case 6:
printf(“Your weight on Uranus is %.2lf\n”,weight0.92);
break;
case 7:
printf(“Your weight on Neptune is %.2lf\n”,weight*1.19);
break;
default:
printf(“Unknown planet\n”);
break;
}
return 0;
}
As the others mentioned, this task is impossible for an inexperienced programmer without using the hints, because scanf() and the & operator are never explained. Fortunately I’m fairly experienced with C so I thought I might try to explain things a little.
The solution for this exercise looks something like this:
#include <stdio.h>
int main() {
float weight = 0;
int planet = 0;
printf("What is your Earth weight?\n> ");
scanf("%f", &weight);
printf("Which planet would you like to fight on?\n> ");
scanf("%d", &planet);
switch(planet) {
case 1:
weight *= 0.38;
break;
case 2:
weight *= 0.91;
break;
case 3:
weight *= 0.38;
break;
case 4:
weight *= 2.34;
break;
case 5:
weight *= 1.06;
break;
case 6:
weight *= 0.92;
break;
case 7:
weight *= 1.19;
break;
default:
printf("Error: Invalid planet supplied.\n");
}
printf("Interplanetary weight: %f\n", weight);
}
The important parts of the code are lines 7-11. This is how you use the aforementioned scanf() function. It takes the general form scanf("<format string>", &<variable>). As we can see, the function takes two parameters.
The first parameter is what’s called a format string. It is a placeholder which includes a format specifier. We learned about these placeholders previously in the Variables lesson, but it was used in printf() rather than scanf(). The placeholder %f lets the compiler know that you’re reading in a floating-point (decimal) number, whereas %d lets the compiler know you’re reading in an integer (%i would signify the same thing).
The second parameter can be thought of as the variable you’re putting the input into. The & operator does have a specific effect here, but it’s tied to a more advanced topic called pointers. For now, just remember that this second parameter is just the name of the variable with & in front of it (for the curious: & retrieves the memory address of the variable as opposed to the number that is currently stored in the variable).
I hope this helps y’all understand a little bit better how to get user input. I don’t know why they introduced it here with no prior mention. I guess they wanted people to research stuff on their own, but in my experience it just demotivates me when I think I understood everything in a lesson and they throw something new at me. It makes me feel like I missed something when really I didn’t at all.
Don’t lose your drive to learn because of this. C is a difficult language to learn, but that just makes it all the more rewarding when your code compiles.
In exactly what sense is this a “review” of conditional statements in C when the exercise requires a firm grasp of material that hasn’t yet been introduced in the C course (viz., storing user input as a variable)?
I’m sure that the C course ranks pretty low on Codecademy’s list of priorities, but this “review” is indicative of the sorry state of QAQC for some of these courses.
//This the code i wrote using switch case and it is working fine #include <stdio.h>
int main() {
double weight;
int x;
printf(“Please enter your current earth weight: “);
scanf(”%lf”, &weight);
printf(“\nI have information for the following planets:\n\n”);
printf(" 1. Mercury\n 2. Venus\n 3. Mars\n 4. Jupiter\n");
printf(" 5. Saturn\n 6. Uranus\n 7. Neptune\n\n");
printf(“Which planet are you visiting? “);
scanf(”%d”, &x);
switch(x){
case 1:printf(“Your weight: %f\n”,weight0.38);
break;
case 2:printf(“Your weight: %f\n”,weight0.91);
break;
case 3:printf(“Your weight: %f\n”,weight0.38);
break;
case 4:printf(“Your weight: %f\n”,weight2.34);
break;
case 5:printf(“Your weight: %f\n”,weight1.06);
break;
case 6:printf(“Your weight: %f\n”,weight0.92);
break;
case 7:printf(“Your weight: %f\n”,weight*1.19);
break;
default:printf(“Invalid\n”);
break;
) below.
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