Errors in Math "tutor"

**eLg** · 07-12-2013

Hi!,
I am a beginner and I am trying to create a program that will randomly generate two numbers from 1 to 10, and an operator. The program will ask for the user to enter the answer. The program is giving me these errors:

Code:

 error C2065: 'num2' : undeclared identifier
error C2143: syntax error : missing ';' before 'type':eek:

Here is the Code

Code:

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<time.h>


int main(){

    int ans;
    int ans1;
    srand((unsigned int)time(NULL));
    int num1 = rand() % 10  + 2;
    int num2 = rand() % 10;
    int operation = rand() % 4 + 1 ;
    

    printf("\tMATH TUTOR\n");
    switch(operation){
    case 1:
        printf("What is %d + %d ?", num1, num2);
        ans = num1 + num2;
        scanf_s("%d", &ans1);
        if(ans == ans1){
            printf("Correct!");
        }else{
            printf("Incorrect! Try Again! Expected answer %d but you typed %d\n", ans, ans1);
            do{
                printf("Enter answer: ");
                scanf_s("%d", &ans1);
                if (ans1==ans){
                    printf("Correct!");
                    break;
                }
            }while( ans1 != ans);
        }
        break;
    case 2:
            printf("What is %d - %d ?", num1, num2);
            scanf_s("%d",&ans1);
            ans = num1 - num2;
            if(ans == ans1){
                printf("Correct!");
            }else{
                printf("Incorrect! Try Again! Expected answer %d but you typed %d\n", ans, ans1);
                do{
                    printf("Enter answer: ");
                    scanf_s("%d", &ans1);
                    if (ans1==ans){
                        printf("Correct!");
                        break;
                    }
                }while( ans1 != ans);
            }
            break;
    case 3:
            printf("What is %d * %d ?", num1,num2);
            scanf_s("%d",&ans1);
            ans = num1 * num2;
            if(ans == ans1){
                printf("Correct!");
            }else{
                printf("Incorrect! Try Again! Expected answer %d but you typed %d\n", ans, ans1);
                do{
                    printf("Enter answer: ");
                    scanf_s("%d", &ans1);
                    if (ans1==ans){
                        printf("Correct!");
                        break;
                    }
                }while( ans1 != ans);
            }
            break;
    case 4:
            printf("What is %d / %d ?", num1, num2);
            scanf_s("%d",&ans1);
            ans = num1 / num2;
            if(ans == ans1){
                printf("Correct!");
            }else{
                printf("Incorrect! Try Again! Expected answer %d but you typed %d\n", ans, ans1);
            do{
                printf("Enter answer: ");
                scanf_s("%d", &ans1);
                if (ans1==ans){
                    printf("Correct!");
                    break;
                }
                }while( ans1 != ans);
            }
            break;
    default:
        printf("nothing");
        break;
    }
        _getch();
        return 0;
}

Can someone please help me?please

**jimblumberg** · 07-12-2013

Since you're using the outdated Microsoft compiler, you'll need to insure your variables are all declared before any of them are used. C90 requires all varialbes to be defined at the beginning of the scope and before any calculations or function calls.

Jim

**eLg** · 07-14-2013

Originally Posted by jimblumberg

Since you're using the outdated Microsoft compiler, you'll need to insure your variables are all declared before any of them are used. C90 requires all varialbes to be defined at the beginning of the scope and before any calculations or function calls.

Jim

Is there a way to change the compiler in VS2010? and I think the variable are defined on top. Did it work in your IDE?

**vart** · 07-14-2013

Originally Posted by eLg

and I think the variable are defined on top.

you are wrong here

Code:

int ans;
    int ans1;
    srand((unsigned int)time(NULL));
    int num1 = rand() % 10  + 2;
    int num2 = rand() % 10;
    int operation = rand() % 4 + 1 ;

This should be

Code:

int ans;
    int ans1;
    int num1;
    int num2;
    int operation;
    srand((unsigned int)time(NULL));
    num1 = rand() % 10  + 2;
    num2 = rand() % 10;
    operation = rand() % 4 + 1 ;

**jimblumberg** · 07-15-2013

Is there a way to change the compiler in VS2010?

No, if you want a different compiler you'll need to download a different IDE, made by someone else. Mircrosoft doesn't support anything other than C90 with their comilers.

Did it work in your IDE?

No, you're program won't compile in my compiler but for other reasons. My compiler doesn't support the non-standard conio.h header file. And it also doesn't support the non-standard scanf_s() function. But after fixing these issues the code does properly complie with my C11 compliant compiler.

Jim

**vart** · 07-15-2013

Originally Posted by jimblumberg

No, if you want a different compiler you'll need to download a different IDE, made by someone else. Mircrosoft doesn't support anything other than C90 with their comilers.

Strictly speaking - you can use different compilers with Microsoft VS IDE

About compilers -they claim that they do not plan to add support of C99 standard as is, but will support "features of C99 standard that are part of C++11 standard"

Does it mean that you have to compile your C code as C++ to get these features - I have no idea...

**eLg** · 07-15-2013

Originally Posted by vart

you are wrong here

Code:

int ans;
    int ans1;
    srand((unsigned int)time(NULL));
    int num1 = rand() % 10  + 2;
    int num2 = rand() % 10;
    int operation = rand() % 4 + 1 ;

This should be

Code:

int ans;
    int ans1;
    int num1;
    int num2;
    int operation;
    srand((unsigned int)time(NULL));
    num1 = rand() % 10  + 2;
    num2 = rand() % 10;
    operation = rand() % 4 + 1 ;

What is wrong in this part?
If I removed unsigned int, it will give the same number.
If I did not removed unsigned int, it will say undeclared variables.

**eLg** · 07-15-2013

Originally Posted by jimblumberg

No, if you want a different compiler you'll need to download a different IDE, made by someone else. Mircrosoft doesn't support anything other than C90 with their comilers.

No, you're program won't compile in my compiler but for other reasons. My compiler doesn't support the non-standard conio.h header file. And it also doesn't support the non-standard scanf_s() function. But after fixing these issues the code does properly complie with my C11 compliant compiler.

Jim

What changes did you do? What is your IDE? Which IDE do you suggest for beginners in C programming?
And about the scanf_s, VS 2010 won't allow me to compile the program if it is scanf().

**vart** · 07-15-2013

Originally Posted by eLg

What is wrong in this part?

Not in this part. In the following statement

and I think the variable are defined on top.

You have variable definitions after the part marked in red.
And so they are not defined "on top" but after some other code.

**vart** · 07-15-2013

Originally Posted by eLg

VS 2010 won't allow me to compile the program if it is scanf().

It will - if you read the error statement and define the suggested macro in your project settings

**eLg** · 07-15-2013

Originally Posted by vart

Strictly speaking - you can use different compilers with Microsoft VS IDE

About compilers -they claim that they do not plan to add support of C99 standard as is, but will support "features of C99 standard that are part of C++11 standard"

Does it mean that you have to compile your C code as C++ to get these features - I have no idea...

if I will compile my code as C++, does that mean that I have to change the name of the libraries I included?

**jimblumberg** · 07-15-2013

What changes did you do?

I removed the conio.h include file and getch(). Then I also changed the non-standard scanf_s() to the standard scanf().

What is your IDE? Which IDE do you suggest for beginners in C programming?

For only C on Windows Pelles C is a good choice. If you need both C and C++ I recommend Code::Blocks with gcc. If you only need C++ then Visual C++ is an acceptable choice in my opinion.

Jim

**eLg** · 07-15-2013

Originally Posted by vart

Not in this part. In the following statement

You have variable definitions after the part marked in red.
And so they are not defined "on top" but after some other code.

oh ok. If I place the srand() above all the codes, all the variable will be undefined, according to VS

**vart** · 07-15-2013

Originally Posted by eLg

oh ok. If I place the srand() above all the codes, all the variable will be undefined, according to VS

So you should (to be compliant with C90)
1. define your vars
2. call srand
3. populate your vars with random data

See my sample in post#4

**eLg** · 07-15-2013

Originally Posted by vart

It will - if you read the error statement and define the suggested macro in your project settings

which macro should I use? The error statement is showing that scanf_s should be used.

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