The code does not seem to execute properly - c

Question

Gets stuck inside of the valid = 0 while loop where it does not get passed scanf and keeps asking for input. The program was designed to accept an integer value for the GPA and then calculate the frequency of each gpa among what had been given.
#include <stdio.h>
int main(void) {
int amount, i, count, valid;
int GPA[200], GPAFreq[4];
valid = 0;
i = 1;
count = 1;
GPA[1] = 0; GPA[6] = 0;
GPA[2] = 0; GPA[7] = 0;
GPA[3] = 0; GPA[8] = 0;
GPA[4] = 0; GPA[9] = 0;
GPA[5] = 0; GPA[10] = 0;
GPAFreq[1] = 0; GPAFreq[3] = 0;
GPAFreq[2] = 0; GPAFreq[4] = 0;
printf("Enter the number of students: ");
scanf("%d", &amount);
while ( i < (amount + 1))
{
i += 1;
while (valid == 0)
{
printf("%d", GPA[i]);
if ( (GPA[i] == 4) || (GPA[i] == 3) || (GPA[i] == 2) || (GPA[i] == 1) )
{
valid = 1;
}
else
{
printf("GPA of student # %d is: ", i);
scanf("%d", &GPA[i]);
}
}
count = 1;
while (count < 5)
{
if (GPA[i] == count)
{
GPAFreq[count] +=1;
}
}
}
count = 1;
while (count < 5)
{
printf("\nGPA %d --- %d student(s).", count, GPAFreq[count]);
count += 1;
}
return 0;
}

Answer 1

When I execute this it does not get stuck on the while(valid == 0) loop, it gets stuck in the 1st while(count < 5) because you do not increment count inside this loop.
There are a few other things that pop out immediately to me in this code that I might as well point out.
You can automatically have all elements of an array set to 0 by declaring like int array[10] = {0}. There are a few ways of doing this (including for loops), but you don't need to manually type each one out like you do in lines 11-18
Arrays are 0 indexed in c, so you start counting from 0, not 1
You increment i at the beginning of the while loop (line 26) before it is accessed. Thus meaning the first index actually being used is 2 (remember it should be 0)
If you are limiting your number of students to 200, you should make sure the user doesn't enter in a number larger than this.
EDIT:
You will also need to reset valid to 0 before the while(valid == 0) loop (you could also just do while(!valid) btw)