for/while loop memory clearing in C - c

Question

In my program I'm messing around with, it simply asks for how many tests one has written and then returns an average. However I've modified it a bit so that it asks if the marks entered are correct.
Problem 1: It doesn't let you input your marks for all your tests
Problem 2: If the marks are wrong it starts over but keep the previous inputs in it's memory? How do I fix the?
Here's the code:
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[]) {
//int variables for grade
unsigned int counter; //number of grades to be entered next
int grade;
int total;
float average;
// user input
int userInput; // amount of tests
int yesNo;
//amount of test passed
unsigned int pass = 0;
unsigned int fail = 0;
int doCount = 1;
//unsigned int test;
//---------------------------------------------------------------------------------------------------//
//standards for program to abide to
total = 0; //Total amount of test to be set to zero, until while statement
counter = 1; //Loop counter to start from one
//---------------------------------------------------------------------------------------------------//
printf ("Please enter amount of test you've written so far: ");
scanf ("%d", &userInput);
//printf ("%d", userInput);
//---------------------------------------------------------------------------------------------------//
do {
//Body of calculations of program
for(counter = 0; counter <= userInput; ++counter) { //for loop that correlates to userInput for amount of passes and test marks
printf ("Please enter percentage mark: "); //prompt for test mark
scanf("%d", &grade);
total = total + grade;
counter = counter + 1;
if (grade >= 40) { //if statement for pass or fail
pass = pass + 1;
} else {
fail = fail + 1;
}
}//end of for loop
printf ("Are the grades entered correct? (1 = yes, 2 = no): "); // user input for yesNo - are inputs correct
scanf ("%d", &yesNo);
if (yesNo == 2) {
} else {
average = ((float)total / userInput); //Getting average for tests so far
//if statement to clarify if you're passing
if (average < 40) {
printf ("\nYou are below sub minimum!\n");
printf ("Your overall average is: %.2f %\n", average);
printf ("Passed: %d\n", pass);
printf ("Failed: %d", fail);
} else if (average >= 75){
printf ("\nYou have a distinction agregate!\n");
printf ("Your overall average is: %.2f %\n", average);
printf ("Passed: %d\n", pass);
printf ("Failed: %d", fail);
} else {
printf ("\nYour overall average is: %.2f %\n", average);
printf ("Passed: %d\n", pass);
printf ("Failed: %d", fail);
}
doCount = 2;
}
} while (doCount == 1);
average = ((float)total / userInput); //Getting average for tests so far
//---------------------------------------------------------------------------------------------------//
getch ();
return 0;
}

Answer 1

In your do while loop, when you come around for your second pass you need to reset your variables. Specifically the total variable should be reset to zero. You do it for the first time outside the do while loop but once it's in the loop for the second pass it doesn't get reset to 0.
As for not reading all test inputs, if it asks for 9 but you need 10 then it likely is a problem with the for loop. I typically use counter++ and not ++counter as it increments the counter after the operation and not before the operation. That may or may not be the reason as I did not run your code, but it is worth looking at.

Answer 2

I've edited your code and commented the changes:
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[]) {
//int variables for grade
unsigned int counter; //number of grades to be entered next
int grade;
int total;
float average;
// user input
int userInput; // amount of tests
int yesNo;
//amount of test passed
unsigned int pass = 0;
unsigned int fail = 0;
int doCount = 1;
//unsigned int test;
//---------------------------------------------------------------------------------------------------//
//standards for program to abide to
total = 0; //Total amount of test to be set to zero, until while statement
counter = 0; //Loop counter to start from zero, It's always better to start from zero
//---------------------------------------------------------------------------------------------------//
printf("Please enter amount of test you've written so far: ");
scanf("%d", &userInput);
//printf ("%d", userInput);
//---------------------------------------------------------------------------------------------------//
do {
//Body of calculations of program
total = 0; //You need to reset total pass and fail
pass = 0;
fail = 0;
for (counter = 0; counter < userInput; ++counter) { //for loop that correlates to userInput for amount of passes and test marks
printf("Please enter percentage mark: "); //prompt for test mark
scanf("%d", &grade);
total = total + grade;
//counter = counter + 1; You DON't need that
if (grade >= 40) { //if statement for pass or fail
pass = pass + 1;
}
else {
fail = fail + 1;
}
}//end of for loop
printf("Are the grades entered correct? (1 = yes, 2 = no): "); // user input for yesNo - are inputs correct
scanf("%d", &yesNo);
if (yesNo == 2) {
}
else {
average = ((float)total / userInput); //Getting average for tests so far
//if statement to clarify if you're passing
if (average < 40) {
printf("\nYou are below sub minimum!\n");
printf("Your overall average is: %.2f %\n", average);
printf("Passed: %d\n", pass);
printf("Failed: %d", fail);
}
else if (average >= 75) {
printf("\nYou have a distinction agregate!\n");
printf("Your overall average is: %.2f %\n", average);
printf("Passed: %d\n", pass);
printf("Failed: %d", fail);
}
else {
printf("\nYour overall average is: %.2f %\n", average);
printf("Passed: %d\n", pass);
printf("Failed: %d", fail);
}
doCount = 2;
}
} while (doCount == 1);
average = ((float)total / userInput); //Getting average for tests so far
//---------------------------------------------------------------------------------------------------//
getch();
return 0;
}