Program suddenly stops working.

This is a discussion on Program suddenly stops working. within the C Programming forums, part of the General Programming Boards category; Hello, I'm fairly new to C, and after taking several examples from the book I decided to write my own. ...

  1. #1
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    Exclamation Program suddenly stops working.

    Hello, I'm fairly new to C, and after taking several examples from the book I decided to write my own. Yet I kept running into several problems with it, so i decided I'd just continue reading, and maybe I'd find the answer there. So I put in another example involving the switch statement, and ran into the same problem.

    The problem is, every time I run the program, it will bring up the little mini window that says "___ has stopped working" or something along those lines. But I think I've linked it to having to get a value from a variable, then using that same variable within the parentheses of a printf() function and using it in an arithmetic equation with another variable. The examples of code that I encountered this problem with were the following:


    Code:
    #include <stdio.h>
    
    int main(void)
    {
    float f, ff;
    char c;
    {
    printf("Type number, operator, number\n");
            
    scanf("%f %c %f", f, c, f);
            
    switch (c)
    {
    case '+':
        printf(" = %f", f + ff);
    case '-':
        printf(" = %f", f - ff);
    case '*':
        printf(" = %f", f * ff);
    case '/':
        printf(" = %f", f / ff);
    default:
        printf("Unknown operator");
    }
    printf("\n\n");
    }
    return 0;
    }
    This is the one from the book, only I had to add the heaer file, the void and the int around the main function, and return 0;. This is taken almost exactly from the book, but I used different names for variables, and indented differently. But I already know that doesn't matter.

    But the examples that I did narrowing it down to the conclusin that it only happened when it has <stdio.h>, printf, and variable arithmetic within it.

    Code:
    #include <stdio.h>
    
    main();
    {
    printf("%d\n" 2 + 2);
    
    return 0;
    }
    Code:
    #include <stdio.h>
    
    main();
    {
    int i = 2;
    
    printf("%d\n" i + i);
    
    return 0;
    }
    Code:
    #include <stdio.h>
    
    main();
    {
    int i;
    
    scanf("%d" i);
    
    printf("%d\n" i + i);
    
    return 0;
    }
    Those three were something similar, I'm not sure what they were exactly, but they were similar to that. I didn't test them, other than the last one, and when I compiled it, it gave me that same error, where it said that the program was not responding, and it needed to close. If it matters, I am using the Digital Mars compiler, the free version, and I'm running it from the command line.

    tl;dr: I have a problem where when I run a program that has a scanf(), and a variable within the printf() function's parentheses that I use with another variable in an arithmetic equation, it gives me the small window saying that the program is not responding andneeds to close. I am using the Digital Mars C compiler, and I'm running the free version from the Command Line. Any advice as to how I can fix this?

  2. #2
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    Add the & to all your non-string scanf() calls:

    scanf("%f %c", &f, &c);

    etc.

    See what that does, I haven't checked the rest of your code.

  3. #3
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    Okay, it works now. It stopped giving me that error. Now, instead, it adds the addresses of the numbers together... but I can go figure that out somewhere else. I don't think it needs to be answered here.

    Thanks for the help!

  4. #4
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    Quote Originally Posted by KittenAqua View Post
    Okay, it works now. It stopped giving me that error. Now, instead, it adds the addresses of the numbers together... but I can go figure that out somewhere else. I don't think it needs to be answered here.

    Thanks for the help!
    From your original posting... you are using ff in an uninitialized state.

  5. #5
    Registered User TheBigH's Avatar
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    Also, you need commas between the arguments in functions:

    Code:
    printf( "%d\n" thing );  /*  WRONG  */
    printf( "%d\n", thing ); /* BETTER */
    Code:
    while(!asleep) {
       sheep++;
    }

  6. #6
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    Oh ya... I was using it uninitialized. It was supposed to be the third variable who's value is gotten from scanf(), but I just didn't even realize it. It's not exactly an easy error to find when you're not told where the error is.

    Other than the bottom 3, which I rewrote hurriedly after deleting and didn't bother to test, I did put commas between arguments in the top one. At least, out of what I can see.

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