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variables values not showing equal

Dnyaneshwar07

Hello everyone,

                       i am using renesas rx231 series microcontroller and E2 studio ide for code development,

                         i have written one small code in which i have taken one signed int whoes value is -3871,and another variable which is also same signed int with value of 61665 which its 2's compliment value  -3871and another same variable i have taken signed int with hex value of -3871 which is 0xF0E1 ,with this i have written one if else statement but it is not working/not showing the same value.

signed int i = -3871;
signed int j = 0xf0e1;
signed int k = 61165;

_Bool m;

void main(void)
{

while(1)
{
R_Config_WDT_Restart();

if(j == k)
{
m = 1;
}
else if(j == i)
{
m = 1;
}
else if(k == i)
{
m = 1;
}
else
{
m = 0;
}
}

}

value of m remains 0 always.why this is happening??

please any can explain this?

Parents

  • You would do yourself a favour by using more modern C coding practice:

    add these includes to the start of every module:

    #include <stdint.h>
    #include <stdbool.h>

    declare 16 bit integers like this:

    uint16_t auto_zero_pw = 12345;

    int16_t temperature = -10;

    and Booleans like this:

    bool alarm_flag = false;

    This way you will know  how many bits your variables are.

    You should never set a bool to values other than true or false and you should never test it against values other than true or false.

    It sounds pedantic but it helps to reduce errors.

    MK

  • in reply to michaelkellett

      If you want to code like that you should use PASCAL, not C.

    AND flags can be anything you want them to be.  This is my code for my wheels. 

     my code for a wheel.R, wheel.L, wheel.C

    The following 5 lines are in my module.h
    #define UP 1:4
    #define DOWN 0:4
    #define MOVING 2:4
    #define PASS 1
    #define FAIL -1

    struct wheels {
    unsigned R:4; 
    unsigned L:4;
    unsigned C:4;
    };

    return( FAIL);

    Writing long and bloated variable names is really never done anymore that's why every module you use should have a corresponding .h where you define the stuff! and BTW I don't ever do L:4 as if you have an 8-bit MCU don't obfuscate the code.  If tried this with pointers then you have a MESS (PASCAL)

  • in reply to phoenixcomm

    Arguments about C coding standards are as never-ending as those about religion.

    However, your suggestion re. Pascal is not rational - almost all micro-controllers are supported by a choice of C compilers, very few are supported by Pascal compilers.

    And I don't know of any certified industrial stregnth Pascal compilers suitable for micro-contollers.

    I code generally according to the MISRA 2012 C standard and Michael Barr's Embedded C Coding Standard 2018 (with modifications which I have documented.)

    I've not yet had a complaint from customers that my variable names are too long and they generally seem to appreciate being able to understand what the code is intended to do.

    You are obviously comfortable with the way you write code, but my suggestion was aimed at the OP who is having some problems.

    Happy debugging.

    MK

  • in reply to michaelkellett
    michaelkellett said:
    Pascal is not rational

    No I was trying to point out the difference in coding styles. The long bloated variable names is how Pascal programmers do it. And even Niklaus Wirth who created it claimed it was for education and not for building large systems. 

    michaelkellett said:
    uint16_t auto_zero_pw = 12345;

      in C this is absurd.  it can be better handled in a module.h file 

    I'm still not sure what this does. (code above).  I have and still do work in 64-bit systems first being M68K, then Sun Sparc..ie this way you get all of the integers 8, 16, 32, 64-bit, and if you are so inclined 128-bit which is a double 64-bit int. 

    in my module.h file I have a list of variable types and names sometimes even an initialized value.  this list I try and keep this in alpha order. (variable names, not types.  I hate to bit-bang my flags by setting them to BOOL, so I always keep them as Int (8-bit) in this way I let the compiler do the work, and I don't have to. I do Misra/JSF C when I write Avionics Stuff for cash! The biggest problem with Misra/Mitter is check the code. The way is to buy the damn French package but it is BIG BUCKS. But I have found out other ways to skin the cat. write code normally and send it to a Misra pretty printer. :))

  • in reply to phoenixcomm

    I didn't say that Pascal was not rational, I said:

    michaelkellett said:
    your suggestion re. Pascal is not rational - almost all micro-controllers are supported by a choice of C compilers, very few are supported by Pascal compilers.

    ie. it is the suggestion of using Pascal in the context of programming micro-controllers that I am commenting on.

    Pascal itself was a fine contribution to computing but isn't very useful now.

    Menaingful variable names are widely used in a variety of programming languages.

    If you like to keep your flags as addressable objects (like int8_t) then using bool should suit you down to the ground. This discussion on StackOverflow should both illuminate and confuse in equal measure.

    https://stackoverflow.com/questions/8014161/in-c-how-much-space-does-a-bool-boolean-take-up-is-it-1-bit-1-byte-or-someth

    MK

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