urgent need hlp..i'm develop a math quiz program thy was several error

Code:

---

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#pragma warning(disable:4996)
int menu();
void additionmenu();
void subtractionmenu();
void multiplicationmenu();




void main()
{
    int choice;
    //printf("You have selected the choice %d",menu());


    if (choice == 1)
    {
        printf("You have selected addition\n");
        additionmenu();
    }
    else if (choice == 2)
    {
        printf("You have selected subtraction\n");
        subtractionmenu();
    }
    else if (choice == 3)
    {
        printf("You have selected multiplication\n");
        multiplicationmenu();
    }
    else
    {
        printf("Invalid choice\n");
    }


    system("pause");
}
int menu()
{
    int choice;
    printf("1.addition\n");
    printf("2.subtraction\n");
    printf("3.multiplication\n");
    printf("Please choose either 1,2 or 3:");
    scanf("%d", &choice);
    return choice;


}


void additionmenu()
{
    char choice;
    printf("Please select the level");
    printf("A level 1");
    printf("B level 2");
    printf("C level 3");
    scanf("%c", &choice);
    if (choice == A)
    {
        printf("You have selected level 1\n");
        additionmenu();
    }
    else if (choice == B)
    {
        printf("You have selected level 2\n");
        subtractionmenu();
    }
    else if (choice == C)
    {
        printf("You have selected level 3\n");
        multiplicationmenu();
    }
    else
    {
        printf("Invalid choice\n");


    }


    int n1, n2, pcans, userans;
    int count = 1, mark = 0;
   


    do {
        srand((unsigned int)time(NULL));
        n1 = rand() % 10;
        n2 = rand() % 10;
        pcans = n1 + n2;


        printf("%d.%d+%d>", count, n1, n2);
        scanf("%d", &userans);
        if (userans == pcans);
        {
            printf("You are right\n");
            mark = mark + 5;
        }
        else
        {
            printf("You are wrong\n");
        }
        count++;
    } while (count <= 3);
    printf("Your score is %d", mark);
}

---

its show error at line 58,63,68,84,96 pls help me

The first problem is you wrote too much code before pressing 'compile'.

So instead of one or two errors, you have lots.

Start here

Code:

---

int menu();
int main()  //!! yes, really!, main returns int
{
    int choice;
    choice = menu();
    printf("You have selected the choice %d\n",choice);
 
 
    system("pause");
}
int menu()
{
    int choice;
    printf("1.addition\n");
    printf("2.subtraction\n");
    printf("3.multiplication\n");
    printf("Please choose either 1,2 or 3:");
    scanf("%d", &choice);
    return choice;
}

---

Test it to see that it compiles and works as expected.

Then add small amounts of your other code, compiling and testing as you go.

its work but how about line 92 its say time is undifined and how i create a sub function under addition for level1,2 and 3

time() is defined in time.h

> and how i create a sub function under addition for level1,2 and 3
You already know how to create functions.

So what about
addEasy()
addMedium()
addDifficult()

at line 57 or the beginning?

> at line 57 or the beginning?
You already know that prototypes go at the start, and the implementations are later on in the file.

Code:

---

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#pragma warning(disable:4996)

int menu();
void additionmenu();
void subtractionmenu();
void multiplicationmenu();
void addEasy();
void addMedium();
void addDifficult();

int main()
{
    int choice = menu();
    printf("You have selected the choice %d",choice);

    if (choice == 1)
    {
        printf("You have selected addition\n");
        additionmenu();
    }
    else if (choice == 2)
    {
        printf("You have selected subtraction\n");
        subtractionmenu();
    }
    else if (choice == 3)
    {
        printf("You have selected multiplication\n");
        multiplicationmenu();
    }
    else
    {
        printf("Invalid choice\n");
    }
    system("pause");
}

int menu()
{
    int choice;
    printf("1.addition\n");
    printf("2.subtraction\n");
    printf("3.multiplication\n");
    printf("Please choose either 1,2 or 3:");
    scanf("%d", &choice);
    return choice;
}

void additionmenu()
{
    char choice;
    printf("Please select the level");
    printf("A level 1");
    printf("B level 2");
    printf("C level 3");
    scanf(" %c", &choice);
    if (choice == 'A')
    {
        printf("You have selected level 1\n");
        addEasy();
    }
    else if (choice == 'B')
    {
        printf("You have selected level 2\n");
        addMedium();
    }
    else if (choice == 'C')
    {
        printf("You have selected level 3\n");
        addDifficult();
    }
    else
    {
        printf("Invalid choice\n");
    }
}

void subtractionmenu() {
  printf("To Do\n");
}

void multiplicationmenu() {
  printf("To Do\n");
}

void addEasy() {
  printf("That's easy\n");
}

void addMedium() {
  printf("That's a bit harder\n");
}

void addDifficult() {
  printf("That's really tricky\n");
}

---

Code:

---

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<time.h>
#pragma warning(disable:4996)


int menu();
void additionmenu();
void subtractionmenu();
void multiplicationmenu();
void addEasy();
void addMedium();
void addDifficult();


int main()
{
    int choice = menu();
    printf("You have selected the choice %d", choice);


    if (choice == 1)
    {
        printf("You have selected addition\n");
        additionmenu();
    }
    else if (choice == 2)
    {
        printf("You have selected subtraction\n");
        subtractionmenu();
    }
    else if (choice == 3)
    {
        printf("You have selected multiplication\n");
        multiplicationmenu();
    }
    else
    {
        printf("Invalid choice\n");
    }
    system("pause");
}


int menu()
{
    int choice;
    printf("1.addition\n");
    printf("2.subtraction\n");
    printf("3.multiplication\n");
    printf("Please choose either 1,2 or 3:");
    scanf("%d", &choice);
    return choice;
}


void additionmenu()
{
    char choice;
    printf("Please select the level");
    printf("A level 1");
    printf("B level 2");
    printf("C level 3");
    scanf("%c", &choice);
    if (choice == 'A' || choice == 'a')
    {
        printf("You have selected level 1\n");
        addEasy();
    }
    else if (choice == 'B' || choice == 'b')
    {
        printf("You have selected level 2\n");
        addMedium();
    }
    else if (choice == 'C' || choice == 'c')
    {
        printf("You have selected level 3\n");
        addDifficult();
    }
    else
    {
        printf("Invalid choice\n");


    }
}




void subtractionmenu() {
    printf("To Do\n");
}


void multiplicationmenu() {
    printf("To Do\n");
}


void addEasy() {
    printf("That's easy\n");
   
    {


        int n1, n2, pcans, userans;
        int count = 1, mark = 0;




        do {
            srand((unsigned int)time(NULL));
            n1 = rand() % 10;
            n2 = rand() % 10;
            pcans = n1 + n2;


            printf("%d.%d+%d>", count, n1, n2);
            scanf("%d", &userans);
            if
                (userans == pcans) {
                printf("You are right\n");
                mark = mark + 5;
            }
            else
            {
                printf("You are wrong\n");
            }
            count++;
        } while (count <= 3);
        printf("Your score is %d", mark);
    }




}


void addMedium() {
    printf("That's a bit harder\n");
}


void addDifficult() {
    printf("That's really tricky\n");
}

---

its stop running after i choose the addEasy and why its display invalid choice before i choose? cannot jump to the addEasy part and display question for user to answer

You need to clear the input buffer.
scanf() reads from input buffer, but doesn't clear it.

Pleae read about c functions before using them, internet is full of documentation.

possible solution
fflush(stdin);
or while ( getchar() != '\n' );

Quote:

---

Originally Posted by Horror

possible solution
fflush(stdin);

---

NO! Never use fflush() on streams that was open for input or input/output where the last operation was input!
Only use fflush() on streams that was open for output or input/output where the last operation was output.

This results in undefined behavor!

Quote:

---

Originally Posted by WoodSTokk

NO! Never use fflush() on streams that was open for input or input/output where the last operation was input!
Only use fflush() on streams that was open for output or input/output where the last operation was output.

This results in undefined behavor!

---

The standard on Linux is as follows

For input streams, fflush() discards any buffered data that has been fetched from the underlying file, but has not been consumed by the application.

Windows behaves like linux in this point.

We use stdin, which is mostly a copy of the keyboard buffer.
Please submit detailed information what system you are refering to and and an example to show how this undefined behavior interacts with stdin.

Other than that, i consider it as quite safe for the example code above.

"The standard on Linux is as follows"

Please quote your source for the "standard"

Considering that I wrote
scanf(" %c", &choice); //!! YES, the leading space is important, it's not idle decoration
to specifically address this buffer problem, one wonders who's paying attention.

Quote:

---

Originally Posted by Horror

The standard on Linux is as follows

For input streams, fflush() discards any buffered data that has been fetched from the underlying file, but has not been consumed by the application.

Windows behaves like linux in this point.

We use stdin, which is mostly a copy of the keyboard buffer.
Please submit detailed information what system you are refering to and and an example to show how this undefined behavior interacts with stdin.

Other than that, i consider it as quite safe for the example code above.

---

The system doesn't matter. C is OS independent! Every beginner should learn programming with the C-Standard in mind.
You can also learn features that some OSes add on top of the C-Standard, but then you know that this is not always available and not standard.
If you learn programming for a specific OS, you will later run into problems if you develop a project on another OS and you will not know why there is a problem.
So, the best practice in this forum is to teach programming along the C-Standard.

I have a cunning plan regarding fflush. We'll see what the standard says!

N1570 April 12, 2011 ISO/IEC 9899:201x

Quote:

---

If stream points to an output stream or an update stream in which the most recent operation was not input, the fflush function causes any unwritten data for that stream to be delivered to the host environment to be written to the file; otherwise, the behavior is undefined.

---

Well that was easy to clear up :) Undefined behavior just as mentioned.

Quote:

---

Originally Posted by Horror

The standard on Linux is as follows

For input streams, fflush() discards any buffered data that has been fetched from the underlying file, but has not been consumed by the application.

Windows behaves like linux in this point.

---

You pulled that out of your ass. Windows works that way, but linux doesn't.

If you have access to a linux system, try the following. Enter two numbers on the same line in response to the first scanf. They will both be printed.

Code:

---

#include <stdio.h>

int main() {
    int n;

    scanf("%d", &n);
    printf("%d\n", n);

    fflush(stdin);

    scanf("%d", &n);
    printf("%d\n", n);

    return 0;
}

---