GCC vs MSVS compiler

Question

I'd like ask why GCC compiles my C-code, while it has errors, which MSVS noticed. I've already found a solution to solve these errors. But I'd like to know, why GCC had not seen them. Here is my code:

#define _USE_MATH_DEFINES
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <time.h>
#include <stdlib.h>


double randomer( double randitude)
{
    double random;
    if(randitude != 0)
    {
        int integerranditude = randitude*1000000;
        int base = rand()%integerranditude;
        random = (2*(base/1000000.0)) - randitude;
        printf( "%lf\n", random);
    }
    else 
    {
        random = 0.0;
    }
    return random;
}

void counttofile(double x, double period, double expression, double amplitude, double random, double randitude)
{
    FILE* wyniki = fopen("wyniki.txt", "wt");
    for(x = 0; x <= period*M_PI*2; x = x + 0.128)
    {
        random = randomer(randitude);
        expression = amplitude*(sin(x) + cos(x)) + random;
        fprintf(wyniki, "(%lf) = %lf\n", x, expression);
        /*expression = sin(x) + cos(x) + random;
        if(fabs(expression) <= fabs(amplitude)) 
        {
            fprintf(wyniki, "(%lf) = %lf\n", x, expression);
        }
        else
        {
            fprintf(wyniki, "(%lf) = poza zakresem\n", x);
        }*/
    }
    fclose(wyniki);
}   
void unitchange(double period, double amplitude)
{
    period = period * 180 / M_PI;
    amplitude = amplitude * 180 / M_PI;
}


int main(void)
{
    srand (time(NULL));
    double x, period, expression, amplitude, randitude, random;
    random = 0;
    int command;
    x = 0;
    printf("Co chciałbyś zrobić? \n1. wygenerowac wartosci funkcji sin(x) + cos(x)\n");
    printf("2. wygenerowac wartosci funkcji sin(x) + cos(x),\n   a nastepnie zaszumic o wskazana amplitude.\n");
    printf("Wpisz numer zadania: ");
    scanf("%d", &command);
    if(command == 1)
    {
            randitude = 0;
            printf("Podam wyniki dzialania sin(x) + cos(x).\nOkresl w jakim zakresie amplitudy mam podac wyniki: ");
            scanf("%lf", &amplitude);
            expression = sin(x) + cos(x);
            printf("\nIle okresow mam policzyc? ");
            scanf("%lf", &period);
            unitchange(period, amplitude);
            counttofile(x, period, expression, amplitude, random, randitude);
    }
    else if(command == 2)
    {
            printf("Podam wyniki dzialania sin(x) + cos(x), zaszumionego o zadana amplitude.\nOkresl w jakim zakresie amplitudy mam podac wyniki: ");
            scanf("%lf", &amplitude);
            expression = sin(x) + cos(x);
            printf("\nIle okresow mam policzyc? ");
            scanf("%lf", &period);
            printf("Amplituda szumu ma wynosić: ");
            scanf("%lf", &randitude); 
            unitchange(period, amplitude);
            counttofile(x, period, expression, amplitude, random, randitude);
    }   
    else
    {
        printf("\nNieprawidlowy numer polecenia. Sprobuj jeszcze raz.");
    }
    int proba = 0;
    for(proba =0; proba <=10; proba ++)
    {
        randomer(randitude);
    }
    return 0;
}

Thanks for help.

Ah, I see a declaration after a statement. Perhaps your problem is the Microsoft compiler does not support C99. MSVS is stuck in the dark ages, gcc is not. — Charlie Burns
– Charlie Burns, Commented Oct 16, 2013 at 19:44

Charlie Burns · Accepted Answer · 2013-10-16 19:49:56Z

4

This will not compile in MSVS because it contains a declaration after a statement. MSVS is based on an early version of C that did not allow this. gcc is based on a later version of C that does support this.

int main(void)
{
    srand (time(NULL));
    double x, period, expression, amplitude, randitude, random;

I believe MSVS is based on C89, this feature was introduced in C99. No doubt someone will correct me if I am wrong.

answered Oct 16, 2013 at 19:49

Charlie Burns

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4 Comments

Luiz Felipe Over a year ago

Actually it compile just fine, tried on Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.30319.01 for 80x86 that comes with VS2010.

Charlie Burns Over a year ago

@LuizFelipe Ok, maybe OP's compiler is out of date. Did you save it is a .c file or .cpp file, that makes a difference.

Luiz Felipe Over a year ago

Yes, you are correct, the C compiler is stuck on C89, but the cpp compiler not, you can force it to use cpp compiler. The cpp compiler has partial support for C++11, but is improving. Here is a good explanation herbsutter.com/2012/05/03/reader-qa-what-about-vc-and-c99

PJTraill Over a year ago

Given that this is meant to be C, compiling it as C++ is a dodgy manoeuvre. But MSVS 2012/2013 finally allow this.

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