StudentsAndGrades

#include <stdio.h>
#include <stdbool.h>
#include <math.h>
#include <string.h>
#include <Windows.h>
#include <conio.h>

#pragma warning(disable : 4996)

#define minStudetsPerGroup 2
#define maxStudentsPerGroup 20

#define maxAllowedCharacters 40

#define minSubjectCount 1
#define maxSubjectsCount 20

#define minGrade 2
#define maxGrade 6

#define tolerance 0.0001

unsigned short inputTheStudentsInTheGroupCount();

unsigned short inputTheSubjectsCount();

void inputStudentNames(char[][maxAllowedCharacters], unsigned short);

void inputNamesForTheSubjects(char[][maxAllowedCharacters], unsigned short);

void removeNewlineCharacterIfItExists(char[]);

void inputGrades(char[][maxAllowedCharacters], char[][maxAllowedCharacters], float[][maxSubjectsCount], unsigned short, unsigned short);

bool isValidGrade(float);

void printAllStudentInfo(char[][maxAllowedCharacters], char[][maxAllowedCharacters], float[][maxSubjectsCount], unsigned short, unsigned short);

void mainMenu(char[][maxAllowedCharacters], char[][maxAllowedCharacters], float[][maxSubjectsCount], unsigned short, unsigned short);

void searchForAStudent(char[][maxAllowedCharacters], char[][maxAllowedCharacters], float[][maxSubjectsCount], unsigned short, unsigned short);

void inputAStudentName(char[][maxAllowedCharacters], char[maxAllowedCharacters], unsigned short);

bool isTheStudentNameInTheGroup(char[][maxAllowedCharacters], char[], unsigned short);

void printStudentInfo(char[][maxAllowedCharacters], char[maxAllowedCharacters], char[][maxAllowedCharacters], float[][maxSubjectsCount], unsigned short, unsigned short);

void searchForAGrade(char[][maxAllowedCharacters], char[][maxAllowedCharacters], float[][maxSubjectsCount], unsigned short, unsigned short);

float inputAGrade(float[][maxSubjectsCount], unsigned short, unsigned short);

bool checkTheStudentsIfTheyHaveTheInputtedGradeForASearch(float[][maxSubjectsCount], float, unsigned short, unsigned short);

void printInformationAboutTheFoundedGrade(float[][maxSubjectsCount], float, unsigned short, unsigned short);

unsigned short targetedGradeCount(float[][maxSubjectsCount], float, unsigned short, unsigned short);

unsigned short studentsWithTheTargetedGradeCount(float[][maxSubjectsCount], float, unsigned short, unsigned short);

void printStudentsInfoWithTheTargetedGrade(char[][maxAllowedCharacters], char[][maxAllowedCharacters], float[][maxSubjectsCount], float, unsigned short, unsigned short);

void pressTheEnterKeyToContinue();

void isCursorVisible(bool);

void clearTheInputBuffer();

int main()
{
    isCursorVisible(false);

    unsigned short studentsInTheGroupCount = inputTheStudentsInTheGroupCount();

    printf("\n\n");

    unsigned short subjectsCount = inputTheSubjectsCount();

    clearTheInputBuffer();

    printf("\n\n");

    char studentNames[maxStudentsPerGroup][maxAllowedCharacters];

    printf("Input names for the students:\n\n");

    inputStudentNames(studentNames, studentsInTheGroupCount);

    printf("\n\n");

    char subjectNames[maxSubjectsCount][maxAllowedCharacters];

    printf("Input names for the subjects:\n\n");

    inputNamesForTheSubjects(subjectNames, subjectsCount);

    printf("\n\n");

    float grades[maxStudentsPerGroup][maxSubjectsCount];

    printf("Input grades for each subject for the students:\n\n");

    inputGrades(studentNames, subjectNames, grades, studentsInTheGroupCount, subjectsCount);

    system("cls");

    // For debugging
    /*
        printAllStudentInfo(studentNames, subjectNames, grades, studentsInTheGroupCount, subjectsCount);

        pressTheEnterKeyToContinue();
    */

    clearTheInputBuffer();

    mainMenu(studentNames, subjectNames, grades, studentsInTheGroupCount, subjectsCount);

    return 0;
}

// Function, which asks for an input for the students count and returns the value

unsigned short inputTheStudentsInTheGroupCount()
{
    unsigned short studentsInTheGroupCount;

    studentsInTheGroupCountInput:
    printf("How many students does the group have? [%d : %d]\n", minStudetsPerGroup, maxStudentsPerGroup);
    printf("The students count is: ");
    scanf("%hu", &studentsInTheGroupCount);

    if ( (studentsInTheGroupCount < minStudetsPerGroup) || (studentsInTheGroupCount > maxStudentsPerGroup) )
    {
        printf("\n\nInvalid input!\n\n");

        goto studentsInTheGroupCountInput;
    }

    return studentsInTheGroupCount;
}

// Function, which asks for an input for the subjects count and returns the value

unsigned short inputTheSubjectsCount()
{
    unsigned short subjectsCount;

    subjectsCountInput:
    printf("How many subjects does the group have? [%d : %d]\n", minSubjectCount, maxSubjectsCount);
    printf("The subjects count is: ");
    scanf("%hu", &subjectsCount);

    if ( (subjectsCount < minSubjectCount) || (subjectsCount > maxSubjectsCount) )
    {
        printf("\n\nInvalid input!\n\n");

        goto subjectsCountInput;
    }

    return subjectsCount;
}

// Function, which asks for inputs for the names of the students

void inputStudentNames(char studentNames[][maxAllowedCharacters], unsigned short studentsInTheGroupCount)
{
    for (unsigned short i = 0; i < studentsInTheGroupCount;)
    {
        printf("Student %s%hu: ", ((i + 1) < 10) ? " " : "", i + 1);

        if (fgets(studentNames[i], maxAllowedCharacters, stdin) != NULL)
        {
            removeNewlineCharacterIfItExists(studentNames[i]);

            i++;
        }

        else
        {
            printf("\n\nToo many inputted characters! The max value of characters is %hu. Input a new name.\n\n", maxAllowedCharacters);
        }
    }
}

// Function, which asks for inputs for the names of the subjects

void inputNamesForTheSubjects(char subjectNames[][maxAllowedCharacters], unsigned short subjectsCount)
{
    for (unsigned short i = 0; i < subjectsCount;)
    {
        printf("Subject %s%hu: ", ((i + 1) < 10) ? " " : "", i + 1);

        if (fgets(subjectNames[i], maxAllowedCharacters, stdin) != NULL)
        {
            removeNewlineCharacterIfItExists(subjectNames[i]);

            i++;
        }

        else
        {
            printf("\n\nToo many inputted characters! The max value of characters is %hu. Input a new name.\n\n", maxAllowedCharacters);
        }
    }
}

/*
    Function, which checks the given string, if it contains a newline character on its last element,
    which in most cases does, because the fgets() function adds it when the user presses the "ENTER / RETURN" key,
    and changes it to the NULL terminator
*/

void removeNewlineCharacterIfItExists(char currentName[])
{
    size_t nameLength = strlen(currentName);

    if ( (nameLength > 0) && (currentName[nameLength - 1] == '\n') )
    {
        currentName[nameLength - 1] = '\0';
    }
}

// Function, which asks for inputs for the grades on each subject and every grade is being checked with a helping function

void inputGrades(char studentNames[][maxAllowedCharacters], char subjectNames[][maxAllowedCharacters], float grades[][maxSubjectsCount], unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    for (unsigned short i = 0; i < studentsInTheGroupCount; i++)
    {
        printf("%s's grades:\n\n", studentNames[i]);

        for (unsigned short j = 0; j < subjectsCount; j++)
        {
            do
            {
                printf("%s: ", subjectNames[j]);
                scanf("%f", &grades[i][j]);

                if (!isValidGrade(grades[i][j]))
                {
                    printf("\n\nInvalid grade! Input a new grade!\n\n");
                }
            } while (!isValidGrade(grades[i][j]));
        }

        printf("\n\n");
    }
}

// Function, which returns either "True / 1" or "False / 0", depending on, if the grade is in a specific range

bool isValidGrade(float grade)
{
    return (grade >= minGrade) && (grade <= maxGrade);
}

// Function, which prints the student's number, their name and each subject's name with the grade the student has

void printAllStudentInfo(char studentNames[][maxAllowedCharacters], char subjectNames[][maxAllowedCharacters], float grades[][maxSubjectsCount], unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    for (unsigned short i = 0; i < studentsInTheGroupCount; i++)
    {
        printf("Student %s%hu: %s\n\n", ((i + 1) < 10) ? " " : "", i + 1, studentNames[i]);

        for (unsigned short j = 0; j < subjectsCount; j++)
        {
            printf("%s: %.2f\n", subjectNames[j], grades[i][j]);
        }

        if (i < (studentsInTheGroupCount - 1))
        {
            printf("\n\n");
        }
    }
}

// Function, which gives a few options, which can be chosen by the user. That's the Main Menu.

void mainMenu(char studentNames[][maxAllowedCharacters], char subjectNames[][maxAllowedCharacters], float grades[][maxSubjectsCount], unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    bool exit = false;

    char choice;

    while (!exit)
    {
        system("cls");

        printf("Main Menu:\n\n\n");

        printf("1. Search a student\n\n");
        printf("2. Search a grade\n\n");
        printf("3. Exit\n\n\n");

        printf("Your choice is: ");
        scanf("%c", &choice);

        switch (choice)
        {
            case '1': searchForAStudent(studentNames, subjectNames, grades, studentsInTheGroupCount, subjectsCount); break;

            case '2': searchForAGrade(studentNames, subjectNames, grades, studentsInTheGroupCount, subjectsCount); break;

            case '3': exit = true;
        }
    }
}

// Function, which searches for a student in the group by inputting a name by a helping function and prints their grades by a helping function

void searchForAStudent(char studentNames[][maxAllowedCharacters], char subjectNames[][maxAllowedCharacters], float grades[][maxSubjectsCount], unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    system("cls");

    clearTheInputBuffer();

    char studentName[maxAllowedCharacters];

    inputAStudentName(studentNames, studentName, studentsInTheGroupCount);

    printStudentInfo(studentNames, studentName, subjectNames, grades, studentsInTheGroupCount, subjectsCount);

    pressTheEnterKeyToContinue();
}

/*
    Function, which asks for an input for the name of the student to be searched for and is being checked,
    if it has a newline character to be changed with a NULL terminator character by a helping function
    and if there's a name in the students' group
*/

void inputAStudentName(char studentNames[][maxAllowedCharacters], char studentName[maxAllowedCharacters], unsigned short studentsInTheGroupCount)
{
    bool isFound = false;

    while (!isFound)
    {
        printf("Input the name of the student you want to search: ");

        if (fgets(studentName, maxAllowedCharacters, stdin) != NULL)
        {
            removeNewlineCharacterIfItExists(studentName);

            if (!isTheStudentNameInTheGroup(studentNames, studentName, studentsInTheGroupCount))
            {
                printf("\n\nA student with this name hasn't been found. Please input a different name.\n\n\n");
            }

            else
            {
                printf("\n\nA student with this name has been found. Here's their information:\n\n\n");

                isFound = true;
            }
        }

        else
        {
            printf("\n\nToo many inputted characters! The max value of characters is %hu. Input a new name.\n\n\n", maxAllowedCharacters);
        }
    }
}

// Function, which checks and returns either "True / 1" or "False / 0", if the given name for searching is present in the students' group

bool isTheStudentNameInTheGroup(char studentNames[][maxAllowedCharacters], char studentName[], unsigned short studentsInTheGroupCount)
{
    for (unsigned short i = 0; i < studentsInTheGroupCount; i++)
    {
        if (!strcmp(studentNames[i], studentName))
        {
            return true;
        }
    }

    return false;
}

// Function, which prints information about a specific student

void printStudentInfo(char studentNames[][maxAllowedCharacters], char studentName[maxAllowedCharacters], char subjectNames[][maxAllowedCharacters], float grades[][maxSubjectsCount], unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    for (unsigned short i = 0; i < studentsInTheGroupCount; i++)
    {
        if (!strcmp(studentNames[i], studentName))
        {
            printf("Student %s%hu: %s\n\n", ((i + 1) < 10) ? " " : "", i + 1, studentNames[i]);

            for (unsigned short j = 0; j < subjectsCount; j++)
            {
                printf("%s: %.2f\n", subjectNames[j], grades[i][j]);
            }

            break;
        }
    }
}

// Function, which searches for students with a specific grade by a helping function and prints their information by a helping function

void searchForAGrade(char studentNames[][maxAllowedCharacters], char subjectNames[][maxAllowedCharacters], float grades[][maxSubjectsCount], unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    system("cls");

    clearTheInputBuffer();

    float targetGrade = inputAGrade(grades, studentsInTheGroupCount, subjectsCount);

    printStudentsInfoWithTheTargetedGrade(studentNames, subjectNames, grades, targetGrade, studentsInTheGroupCount, subjectsCount);

    pressTheEnterKeyToContinue();
}

/*
    Function, which asks for an input for the grade to be searched for and is being checked,
    if it is valid by a helping function and if there's a student who has it in the students' group
*/

float inputAGrade(float grades[][maxSubjectsCount], unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    float targetGrade = 0.0f;

    bool isFound = false;

    while ( (!isFound) && (!isValidGrade(targetGrade)) )
    {
        printf("Input a grade you want to search: ");
        scanf("%f", &targetGrade);

        if (!isValidGrade(targetGrade))
        {
            printf("\n\nIvalid input! Input a new grade.\n\n\n");
        }

        else
        {
            if (!checkTheStudentsIfTheyHaveTheInputtedGradeForASearch(grades, targetGrade, studentsInTheGroupCount, subjectsCount))
            {
                printf("\n\nThere's no student with this grade. Please input a different grade.\n\n\n");
            }

            else
            {
                printInformationAboutTheFoundedGrade(grades, targetGrade, studentsInTheGroupCount, subjectsCount);

                isFound = true;
            }
        }
    }

    return targetGrade;
}

// Function, which checks, if a student has the targeted grade, and returns either "True / 1" or "False / 0"

bool checkTheStudentsIfTheyHaveTheInputtedGradeForASearch(float grades[][maxSubjectsCount], float targetGrade, unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    for (unsigned short i = 0; i < studentsInTheGroupCount; i++)
    {
        for (unsigned short j = 0; j < subjectsCount; j++)
        {
            if (fabs(grades[i][j] - targetGrade) < tolerance)
            {
                return true;
            }
        }
    }

    return false;
}

/*
    Function, which prints information for the count of the grades, matching the targeted one, by a helping function
    and the count of the students, having the targeted grade, by a helping function
*/

void printInformationAboutTheFoundedGrade(float grades[][maxSubjectsCount], float targetGrade, unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    unsigned short targetedGradeCounter = targetedGradeCount(grades, targetGrade, studentsInTheGroupCount, subjectsCount);

    unsigned short studentsWithTheTargetedGradeCounter = studentsWithTheTargetedGradeCount(grades, targetGrade, studentsInTheGroupCount, subjectsCount);

    printf("\n\nThere %s %hu grade%s matching the targeted grade (%.2f), %hu of the students %s at least one grade on a subject which matches the targeted one.",
        (targetedGradeCounter == 1) ? "is" : "are",
        targetedGradeCounter,
        (targetedGradeCounter == 1) ? "" : "s",
        targetGrade,
        studentsWithTheTargetedGradeCounter,
        (targetedGradeCounter == 1) ? "has" : "have");
    printf(" Here %s their information:\n\n\n", (targetedGradeCounter == 1) ? "is" : "are");
}

// Function, which returns the count of the grades, matching the targeted one

unsigned short targetedGradeCount(float grades[][maxSubjectsCount], float targetGrade, unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    unsigned short targetedGradeCounter = 0;

    for (unsigned short i = 0; i < studentsInTheGroupCount; i++)
    {
        for (unsigned short j = 0; j < subjectsCount; j++)
        {
            if (fabs(grades[i][j] - targetGrade) < tolerance)
            {
                targetedGradeCounter++;
            }
        }
    }

    return targetedGradeCounter;
}

// Function, which returns the count of the students, having the targeted grade

unsigned short studentsWithTheTargetedGradeCount(float grades[][maxSubjectsCount], float targetGrade, unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    unsigned short studentsWithTheTargetedGradeCounter = 0;

    for (unsigned short i = 0; i < studentsInTheGroupCount; i++)
    {
        for (unsigned short j = 0; j < subjectsCount; j++)
        {
            if (fabs(grades[i][j] - targetGrade) < tolerance)
            {
                studentsWithTheTargetedGradeCounter++;

                break;
            }
        }
    }

    return studentsWithTheTargetedGradeCounter;
}

// Function, which prints information for the students, who have a matching grade on a specific subject

void printStudentsInfoWithTheTargetedGrade(char studentNames[][maxAllowedCharacters], char subjectNames[][maxAllowedCharacters], float grades[][maxSubjectsCount], float targetGrade, unsigned short studentsInTheGroupCount, unsigned short subjectsCount)
{
    bool hasTargetedGrade;

    for (unsigned short i = 0; i < studentsInTheGroupCount; i++)
    {
        hasTargetedGrade = false;

        for (unsigned short j = 0; j < subjectsCount; j++)
        {
            if (fabs(grades[i][j] - targetGrade) < tolerance)
            {
                if (!hasTargetedGrade)
                {
                    printf("Student %s%hu: %s\n", ((i + 1) < 10) ? " " : "", i + 1, studentNames[i]);

                    hasTargetedGrade = true;
                }

                printf("%s: %.2f\n", subjectNames[j], grades[i][j]);
            }
        }

        if (hasTargetedGrade)
        {
            printf("\n");
        }
    }
}

// Function, which waits the user to press the "ENTER / RETURN" key

void pressTheEnterKeyToContinue()
{
    printf("\n\n\nPress \"ENTER\" to go back to the Main Menu");

    while (_getch() != 13); // "\r" - The "ENTER / RETURN" key
}

// Function, which decides to either turn on or turn off the cursor by giving a bool value either "true / 1" or "false / 0"

void isCursorVisible(bool isVisible)
{
    HANDLE consoleHandle = GetStdHandle(STD_OUTPUT_HANDLE);

    CONSOLE_CURSOR_INFO cursorInfo;
    GetConsoleCursorInfo(consoleHandle, &cursorInfo);

    cursorInfo.bVisible = isVisible;
    SetConsoleCursorInfo(consoleHandle, &cursorInfo);
}

// Function, which clears the input buffer from the newline character

void clearTheInputBuffer()
{
    char character = getchar();

    while ( (character != '\n') && (character != EOF) );
}