C Teacher Usage Grading Program

Question

I am trying to make a program so that the teacher can type in a number and it will output the corresponding alphabetical grade in C. Here is what I have so far, I am trying to make the console program stay open until a teacher types in exit or clicks the X icon. I appreciate any help.

#include <stdio.h>
#include<stdlib.h>
#define exit -1

int main(void) {

    int grade;


    printf("Enter student grade: ");
    scanf_s("%d", &grade);
    printf("Students grade is: %d", grade);

    while (grade != exit) {

        if (grade < 65)
        {
            printf("\nStudent grade is: F\n");
        }
        else if (grade <= 69)
        {
            printf("\nStudent grade is: D\n");
        }
        else if (grade <= 79)
        {
            printf("\nStudent grade is: C\n");
        }
        else if (grade <= 89)
        {
            printf("\nStudent grade is: B\n");

        }
        else if (grade <= 100)
        {
            printf("\nStudent grade is: A\n");
        }
        else if (grade == exit) {
        #define EXIT_SUCCESS 0;
        }
        break;
    }
    printf("Enter student grade: ");
    scanf_s("%d", &grade);
    printf("Students grade is: %d", grade);
    return 0;
}

Answer 1

Figured it out, thanks for your help.

#include <stdio.h>
#include<stdlib.h>
#define exit -1

int main(void) {

    int grade;


    printf("Enter student grade , or '-1' to exit \n");
    scanf_s("%d", &grade);
    while (grade != exit) {
        printf("Students grade is: %d", grade);
        if (grade < 65)
        {
            printf("\nStudent grade is: F\n");
        }
        else if (grade <= 69)
        {
            printf("\nStudent grade is: D\n");
        }
        else if (grade <= 79)
        {
            printf("\nStudent grade is: C\n");
        }
        else if (grade <= 89)
        {
            printf("\nStudent grade is: B\n");

        }
        else if (grade <= 100)
        {
            printf("\nStudent grade is: A\n");
        }
        else if (grade == exit) {
            exit;
        }
        printf("Enter student grade , or '-1' to exit \n");
        scanf_s("%d", &grade);
    }
    fgetc(stdin);
    return 0;
}

Answer 2

A few things before the answer: Please do some research, learn, and understand this code before you submit it. I'm not saying you will, but lots of students I went to school with would blindly copy and paste their homework and this only hurts you in the long run. It's not as complicated as you think, once you learn the logic it becomes way easier.

Some Resources that I recommend you study for this homework: Convert char array to a int number in C, https://www.tutorialspoint.com/c_standard_library/c_function_sscanf.htm

If you want to be able to enter the word "exit" or an int in the same array, you need to write it to a char array. The idea is to convert the string to an int if it is a number. You can do This with something like sscanf or atoi.

If you were to type "exit" it is case sensitive. You can make all the cases lower or upper case using a for loop. In my case I take the user input and compare it to my array exit_Array. If it returns 0 ( It matches) it moves on to the next stage which is exiting the program.

If it is an int it moves on to phase 1, which is grading. Once it is graded it lowers the phase by 1 so it becomes 0 (enters the first loop again). It will do this over and over until the user enters "exit".

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
char input_Array[3];
char exit_Array[] = "exit";

int grade;
int phase = -1;

phase++;
while(phase == 0)
{
    printf("Enter student grade: ");
    scanf("%s", input_Array);

    // Converts all letters to lower case so it can be Exit, eXiT, etc.
    for(int i = 0; i <= strlen(input_Array); i++)
    {
        input_Array[i] = tolower(input_Array[i]);
    }

    // Exit Input
    if(strcmp(input_Array, exit_Array) == 0)
    {
        printf("Goodbye!");
        exit(0);
    }
    else
    {
        // Convert String to Number
        grade = atoi(input_Array);
    }
    phase++;

    while(phase == 1)
        {
            if (grade < 65)
                {
                    printf("Student grade is: F\n");
                }
            else if (grade <= 69)
                {
                    printf("Student grade is: D\n");
                }
            else if (grade <= 79)
                {
                    printf("Student grade is: C\n");
                }
            else if (grade <= 89)
                {
                    printf("Student grade is: B\n");
                }
            else if (grade <= 100)
                {
                    printf("Student grade is: A\n");
                }
            phase--;
        }
}

return 0;
}