Trouble passing data into a pointer in C [closed] - c

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I am trying to create a function that will add the total of 3 exams, divide them by 4 and then multiply them by .4 and pass the resulting number back to a pointer. I'm not sure which line number is the issue or what I am missing here.
I'm new to coding in C and new to Stack Overflow.
void calcExams(void)
{
int i;
float examTotal;
float *calcExams;
float oneExam;
for (i = 0; i > 3;)
{
printf("\n Enter an exam grade: ");
scanf("%f", oneExam);
examTotal = examTotal + oneExam;
*calcExams = examTotal / 4 * .4;
}
}

Answer 1

Problem 1:
A pointer, as the name hints at, should point somewhere, i.e to some valid memory location, as you have it, it's uninitialized, it points nowhere, or more accurately, to some random memory location given by whatever residual value is stored in it when it's declared, accessing such memory location by dereferencing the pointer amounts to undefined behavior.
That is to say your pointer must be initialized before it's used, either by way of memory allocation or otherwise making it point to some valid variable:
#include <stdlib.h>
//...
float *calcExams = malloc(sizeof *calcExams);
Or:
float some_variable;
float *calcExams = &some_variable;
Problem 2:
scanf expects as an argument the address of the variable on which to store the inputed value, but you are passing this variable by value, you need:
scanf("%f", &oneExam);
^